We granted certiorari to consider whether the present action for personal injuries filed by Vineyard against Fowler and Georgia Hi-Lift is barred by res judicata. The bar would result from Vineyard’s voluntary dismissal with prejudice of his cross-claim for contribution against Fowler and Georgia Hi-Lift in a previous action in which Vineyard was a co-defendant with Fowler and Georgia Hi-Lift. We reverse the Court of Appeals’ holding that res judicata did not bar the personal injury action, Vineyard v. Fowler, 197 Ga. App. 453 (398 SE2d 709) (1990).
On January 17, 1987, Vineyard (a MARTA bus driver) and Fowler (the driver of a truck owned by Georgia Hi-Lift) were involved in a collision in which 26 persons were injured. Two injured bus passengers filed separate actions against the same defendants — MARTA, Vineyard, Fowler, and Georgia Hi-Lift (hereafter Fowler and Georgia Hi-Lift will be referred to as “the Hi-Lift defendants”). In each of those cases, Vineyard and MARTA filed cross-claims against the Hi-Lift defendants for contribution and indemnification. The parties settled both passengers’ suits out of court, and in July 1988 Vineyard and MARTA voluntarily dismissed with prejudice their cross-claims against the Hi-Lift defendants.1
*455In August 1988 Vineyard sued the Hi-Lift defendants for damages resulting from the personal injuries Vineyard sustained in the collision. The Hi-Lift defendants moved for summary judgment, arguing that, because Vineyard dismissed with, prejudice his cross-claims for contribution and indemnification, res judicata barred Vineyard’s personal injury action. The trial court granted the Hi-Lift defendants’ motion for summary judgment, holding that OCGA § 9-12-40, our res judicata statute, barred Vineyard’s suit.
The Court of Appeals reversed Vineyard v. Fowler, supra, 197 Ga. App. at 453, and we granted the Hi-Lift defendants’ application for certiorari to consider whether Vineyard’s current action is barred by the doctrine of res judicata.
Several important issues, concerning two statutes, are presented for resolution. One statute is § 9-12-40, which is “a codification of Georgia’s basic common law rule of res judicata.” Lawson v. Watkins, 261 Ga. 147, 148 (401 SE2d 719) (1991). The other statute is OCGA § 9-11-13 (g), which provides for the permissive filing of cross-claims. We must decide whether the requirements of res judicata have been met in this case, and, if so, whether res judicata should bar Vineyard’s current action or whether, because the personal injury claim was a permissive cross-claim in the first action, Vineyard should not now be barred from asserting it. We conclude that the requirements of res judicata have been met in this case, and that res judicata should operate as a bar to Vineyard’s personal injury claim, despite the permissive cross-claim provision of § 9-11-13 (g). We therefore must reverse the judgment of the Court of Appeals.
1. OCGA § 9-12-40, our res judicata statute, provides that
[a] judgment of a court of competent jurisdiction shall be conclusive between the same parties and their privies as to all matters put in issue or which under the rules of law might have been put in issue in the cause wherein the judgment was rendered until the judgment is reversed or set aside.
For a prior action to bar a subsequent action under the doctrine of res judicata, several requirements must be met: The first action must have involved an adjudication by a court of competent jurisdiction, McCracken v. City of College Park, 259 Ga. 490, 491 (2) (384 SE2d 648) (1989); the two actions must have an identity of parties and subject matter, Lawson v. Watkins, supra, 261 Ga. at 148; and the party against whom the doctrine of res judicata is raised must have had a *456full and fair opportunity to litigate the issues in the first action, Winters v. Pund, 179 Ga. App. 349, 352 (346 SE2d 124) (1986); Sil-Flo, Inc. v. SFHC, Inc., 917 F2d 1507, 1520 (18) (10th Cir. 1990).
2. In determining whether the requirements of res judicata have been satisfied, we first address Vineyard’s argument that a voluntary dismissal with prejudice, without order or approval of the trial court, cannot be considered a judgment on the merits for purposes of our res judicata statute, § 9-12-40. We disagree.
In cases in which there has been a voluntary dismissal of an action with prejudice upon agreement of the parties and accomplished with an order of court, we have held that the dismissal operates as an adjudication upon the merits and bars the right to bring another action on the same claim. See Rowland v. Vickers, 233 Ga. 67, 68 (209 SE2d 592) (1974); Marchman & Sons v. Nelson, 251 Ga. 475, 477 (306 SE2d 290) (1983).2 We did not turn these cases upon the fact that the dismissal was pursuant to order of court, and we can see no reason for distinguishing those cases from cases in which a voluntary dismissal with prejudice has been accomplished by the parties filing a stipulation of dismissal with the clerk of court. We believe that a dismissal “with prejudice” should have the same effect in both instances.
OCGA § 9-11-41 (a), by analogy, lends support to our conclusion that a voluntary dismissal with prejudice but without order of court should act as res judicata. OCGA § 9-11-41 (a) provides that a plaintiff’s third voluntary dismissal, without order of court, operates as an adjudication upon the merits. This statute thus makes a third voluntary dismissal a dismissal with prejudice, and even though the dismissal is not by court order, it bars a subsequent suit under the doctrine of res judicata, T. V. Tempo v. T. V. Venture, 182 Ga. App. 198, 199-201 (1) (355 SE2d 76) (1987).
Finally, we note that commentators, as well as other courts, have concluded that a voluntary dismissal with prejudice, unaccompanied by any court order or approval, is a judgment on the merits for purposes of res judicata. Wright & Miller, Federal Practice and Procedure: Civil, § 2367; 5 Moore’s Federal Practice, §§ 41.02 [5] and 41.05 [2]; Astron Industrial Assoc. v. Chrysler Motors Corp., 405 F2d 958, 960 (1) (5th Cir. 1968).
For the foregoing reasons, we conclude that Vineyard’s voluntary dismissal with prejudice constitutes a judgment on the merits for purposes of res judicata. Anything to the contrary contained in Market Ins. Corp. v. IHM, Inc., 192 Ga. App. 441, 442 (2) (385 SE2d 307) (1989), is overruled.
*4573. We next examine whether the prior action and the instant action involve an identity of parties and subject matter.
(a) Vineyard’s cross-claims and his instant personal injury claim involve an identity of parties. Although the parties in the first litigation were the same, it is still necessary to examine whether Vineyard was in an adversarial relationship with Fowler and Georgia Hi-Lift in that litigation. If he was not, then Vineyard is not bound by the rules of rds judicata. See Restatement of Judgments 2d, §§34 and 38. We conclude that the cross-claims for indemnification and contribution placed Vineyard in an adversarial relationship with Fowler and Georgia Hi-Lift.
By asserting cross-claims for contribution and indemnification, Vineyard sought affirmative relief from Fowler and Georgia Hi-Lift and thus was in an adversarial relationship with them. A condition to asserting a cross-claim is that the co-party asserting it must actually seek affirmative relief against the co-party against whom it is asserted. Wright, Miller & Kane, Federal Practice and Procedure: Civil 2d, § 1431. As OCGA § 9-11-13 (g) and Federal Rule of Civil Procedure (FRCP) 13 (g) specifically permit a party to cross-claim for contribution or indemnification, the rules contemplate that such a cross-claim asserts a claim for affirmative relief. This conclusion is inescapable, considering that a party bringing such a claim is asserting
that the party against whom it is asserted is or may be liable to the cross-claimant for all or part of a claim asserted in the action against the cross-claimant. [OCGA § 9-11-13 (g); FRCP 13 (g).]
Moreover, Restatement of Judgments 2d, § 38, provides that the necessary adversarial relationship between co-parties is satisfied
where the claims or defenses in the pleadings put parties in an adversarial relation to each other even though they may also be aligned together against a third party. This relation arises between defendants who are parties to a cross-claim, . . . Where such claims or defenses have been made, the rules of merger and bar . . . are applicable. [Id. Comment (a).]
For the foregoing reasons, we conclude that Vineyard’s cross-claims put him in an adversarial relationship with Fowler and Georgia Hi-Lift, and that he is bound by the rules of res judicata.3
*458(b) Moreover, we conclude the cross-claims and the personal injury claim involve an identity of subject matter.
In Lawson v. Watkins, supra, 261 Ga. at 149, we noted that
OCGA § 9-12-40 is a codification of Georgia’s common law rule of res judicata. The language used in the statute was drawn from Watkins v. Lawton, 69 Ga. 671 (1882), where this court held:
A judgment is conclusive as to all matters put in issue, or which, under the rules of law, might have been put in issue, in a former suit between the same parties concerning the same subject matter in a court of competent jurisdiction. [Emphasis supplied.]
Thus, one must assert all claims for relief concerning the same subject matter in one lawsuit and any claims for relief concerning that same subject matter which are not raised will be res judicata pursuant to OCGA § 9-12-40.
In the instant case it is beyond dispute that Vineyard’s cross-claims and personal injury claim arose from the same subject matter — the accident between the bus Vineyard was driving and the truck Fowler was driving.
4. The final requirement for res judicata is that Vineyard must have had a full and fair opportunity to litigate his personal injury claim in the prior litigation. Although several circumstances point toward the conclusion that Vineyard did not have a full and fair opportunity to litigate his claim, we conclude, on balance, that he did have a full and fair opportunity.
One factor indicating Vineyard did not have a full and fair opportunity is that, according to an affidavit of Vineyard’s attorney, before August 1988 Vineyard had not fully determined the permanency of his injuries. Another factor is that on his cross-claims Vineyard was represented by MARTA’s attorney, who had no interest in *459representing Vineyard on his personal injury claim. A third factor is the possible ill effect of requiring that a defendant who cross-claims for his personal injuries bring in separate counsel to litigate his personal injury claim as part of the round of litigation in which he is a defendant. Forcing litigation of the personal injury claim as a cross-claim during that proceeding might confuse the jury and lead to its giving less attention to the personal injury claim than if it were litigated as an independent action.
Although these considerations are of real concern, we conclude that Vineyard had a full and fair opportunity to present his claim in the first action. First, Vineyard had employed his present attorney at the time of the first action, and could have had the attorney assert his personal injury claim in the first action. Second, although Vineyard claims he needed to wait until August 1988 to file his claim for personal injuries, the first action was not dismissed until July 1988, and Vineyard, if he had filed his personal injury claim in the first action, could have asked the court for a continuance to permit Vineyard to gain more information regarding the permanency of his injuries. Third, if Vineyard perceived any prejudice that might have arisen from trying his personal injury claim in the context of the first action, Vineyard could have moved the trial court to separate that claim from the other claims in that action. OCGA §§ 9-11-13 (i) and 9-11-42 (b). Fourth, the first action was not in an inconvenient forum for Vineyard, as his subsequent personal injury claim was filed in the same superior court as the first action.
After balancing the relevant factors, we conclude that Vineyard had a full and fair opportunity to litigate his personal injury claim.
5. OCGA § 9-11-13 (g) makes cross-claims permissive. Having decided that the requirements of res judicata have been met in the instant case, we must address Vineyard’s argument that applying res judicata to defeat his personal injury claim would have the effect of making it a compulsory cross-claim, which he contends would be impermissibly inconsistent with the policy behind § 9-11-13 (g). Vineyard’s argument must fail, however, because we have held that res judicata bars a party who foregoes an opportunity to file a permissive cross-claim from bringing the claim in a subsequent action. Citizens Exchange Bank of Pearson v. Kirkland, 256 Ga. 71 (344 SE2d 409) (1986).4
*4606. Having found that all the requirements of res judicata are met in the instant case and that § 9,-11-13 (g) does not prohibit the application of res judicata to Vineyard’s personal injury claim, we hold that Vineyard’s personal injury action is barred by the doctrine of res judicata.
Judgment reversed.
All the Justices concur, except Clarke, C. J., Smith, P. J., and Benham, J., who dissent.Although MARTA’s counsel represented Vineyard in the bus passengers’ suits, Vineyard had retained his present counsel before filing his cross-claim for contribution. Vine*455yard’s counsel swore in an affidavit filed in the trial court that he did not assert the present claim for personal injuries before August 1988 because he wanted to wait to determine the extent of Vineyard’s permanent injuries.
Marchman, supra, 251 Ga., does not indicate whether the voluntary dismissal was with or without order of court. However, for purposes of our discussion, we will assume that the dismissal was accomplished by order of court.
The dissent relies on Hellenic Lines, Ltd. v. Exmouth, 253 F2d 473 (2nd Cir. 1958), to support its position that a claim for indemnity or contribution does not place co-parties in an *458adversarial relationship. However, Hellenic Lines is distinguishable from the instant case, as in that case the co-parties did not assert cross-claims for contribution or indemnification in the first action. Here, Vineyard did assert cross-claims for contribution and indemnification, and thus placed the parties in an adversarial relationship.
Moreover, the court in Hellenic Lines relied on language from the Restatement of Judgments, First, § 82, Comment (b), to the effect that each co-party’s attempt to show that the other was solely responsible for the accident does not make the issue of negligence res judicata between them. The Restatement of Judgments 2d, § 38, substantially departs from the first Restatement on this issue. See Restatement of Judgments 2d, § 38, Reporter’s Note. Thus, even under the facts of Hellenic Lines, the court’s decision in Hellenic Lines is now questionable.
Note that the author of the present opinion dissented to the decision in Kirkland. However, I am now constrained to follow that decision. Moreover, even if this Court had followed the reasoning of my dissent, I would still hold in this case that res judicata bars Vineyard’s personal injury claim, even though it was a permissive cross-claim in the first action. The reason is that Vineyard, unlike Kirkland, asserted a cross-claim in the first action. If a co-party asserts a cross-claim, it is reasonable that the party must also assert all claims arising from that same subject matter at that time or risk preclusion under the doc*460trine of res judicata. See Greenbaum, Jacks or Better to Open: Procedural Limitations on Co-Party and Third-Party Claims, 74 Minn. L. Rev. 507, p. 542 (1990). Here, Vineyard’s cross-claims in the first action and his personal injury claim arise from the same subject matter. Res judicata should thus defeat his personal injury claim.