The State appeals a district court ruling granting James Johnson’s application for postconviction relief. The State contends the district court erred in determining Johnson’s trial counsel rendered ineffective assistance by failing to object to certain testimony.
On July 10, 1987, the State charged James Johnson by amended trial information with three counts of second-degree sexual abuse. At trial, the following exchange occurred, without objection, between the prosecutor and a State’s witness:
Q. Ms. Harlan [defense counsel] asked you about whether children can make accusations as to sexual abuse. Do you have any opinion with relation to Lora and Kora? A. Yes I do.
Q. What would that opinion be? A. My opinion is that they are telling the truth and that they are credible.
The jury convicted Johnson on two of the three charges. The district court then entered judgment and sentenced Johnson to consecutive terms of imprisonment not to exceed twenty-five years each. The supreme court affirmed Johnson’s convictions on further review in State v. Johnson, 445 N.W.2d 337 (Iowa 1989).
On October 12, 1989, Johnson filed an application for postconviction relief. He alleged his trial counsel rendered ineffective assistance by failing to object to the above testimony, which he claimed was in direct violation of the supreme court’s decision in State v. Myers, 382 N.W.2d 91 (Iowa 1986).
At the postconviction hearing, Johnson’s trial counsel testified that while she was not familiar with Myers she was aware that the challenged testimony was improper. She maintained, however, that she chose not to object to such testimony because it would detract from her theory of defense. She stated that her theory was to undermine the social worker’s credibility by demonstrating that the worker had not noticed any signs of sexual abuse in her long relationship with the family until the allegations against Johnson arose. Counsel also pointed out that it was her practice to raise very few objections before the jury.
On January 22, 1992, the district court entered its ruling on the application for postconviction relief. The court ruled that Johnson’s trial counsel rendered ineffective assistance by failing to object to the challenged testimony either at trial or in a pretrial motion in limine. The court noted that the testimony was elicited solely to bolster the testimony of the alleged victims. The children’s testimony apparently was the only link between the defendant and the sexual abuse.
The State appeals, contending trial counsel’s actions were justifiable in light of the theory of defense. Johnson responds, claiming the State has waived error on the issue of whether Johnson was prejudiced by counsel’s alleged failure since the State did not argue prejudice during Johnson’s postconviction trial or appeal.
Ordinarily, our review of postconviction relief proceedings is for errors of law. Hinkle v. State, 290 N.W.2d 28, 30 (Iowa 1980). However, when a postconviction petitioner asserts violation of constitutional safeguards — such as ineffective assistance of counsel — we make our own evaluation based on the totality of the circumstances. This is the equivalent of de novo review. Id.
Our ultimate concern in claims of ineffective assistance is with the “fundamental fairness of the proceeding whose result is being challenged.” State v. Risdal, 404 N.W.2d 130, 131 (Iowa 1987) (quoting Strickland v. Washington, 466 U.S. 668, 696, 104 S.Ct. 2052, 2069, 80 L.Ed.2d 674, 699 (1984)). Ineffective assistance is measured by whether “counsel’s conduct so undermined the proper functioning of the adversarial process that the trial cannot be relied on as having produced a just result.” Strickland, 466 U.S. at 686, 104 S.Ct. at 2064, 80 L.Ed.2d at 692-93; see Schertz v. State, 380 N.W.2d 404, 408 (Iowa 1985).
In order for the appellant to prevail, the record must indicate (1) counsel failed to perform an essential duty and (2) prejudice resulted therefrom. State v. *530Hrbek, 336 N.W.2d 431, 436 (Iowa 1983). In evaluating counsel’s performance, we presume that counsel acted competently. See Risdal, 404 N.W.2d at 131.
In the present case, the postconviction trial court concluded that Johnson’s trial counsel was ineffective by not objecting to testimony by a social worker that, in the social worker’s opinion, the complainant children were truthful and credible. We affirm. The social worker’s opinion testimony that the complainant children were credible witnesses who were telling the truth clearly violates the supreme court’s holding in Myers.
In Myers the defendant appealed his conviction and sentence for indecent contact with a child because the State’s expert was permitted to testify, over defendant’s objection, that children almost never lie about sexual abuse. The Myers court reversed the conviction and remanded the case for a new trial after concluding the trial court abused its discretion in admitting the challenged expert testimony, thereby depriving the defendant of a fair trial. The court determined the expert opinions in the case had the same effect as directly opining on the truthfulness of the complaining witness, and the court held, “we conclude that expert opinions as to the truthfulness of a witness is (sic) not admissible pursuant to [Iowa Rule of Evidence] 702.” Id. at 97. The court explained:
The ultimate determination of the credibility or truthfulness of a witness is not “a fact in issue,” but a matter to be generally determined solely by the jury.... A witness is not permitted to express an opinion as to the ultimate fact of the accused’s guilt or innocence. [Citation omitted]. In this case the trial court admitted expert testimony relating to the truthfulness of the complaining witness. We believe the effect of the opinion testimony was to improperly suggest the complainant was telling the truth and, consequently, the defendant was guilty. We conclude the opinion testimony crossed that “fine but essential” line between an “opinion which would be truly helpful to the jury and that which merely conveys a conclusion concerning defendant’s legal guilt.” [Citation omitted.]
Id. at 97-98.
In the present case the social worker directly opined on the truthfulness and credibility of the complaining witnesses, and defense counsel failed to object. The court in State v. Tracy, 482 N.W.2d 675 (Iowa 1992), faced a similar situation. There the defendant appealed his conviction of third-degree sexual abuse after the State’s expert witness testified, “there are probably no more than two or three children per thousand who come forth with such a serious allegation who are found later to be dishonest.” Id. at 678.
In Tracy the supreme court remanded the case for the purpose of making a record on the issue of ineffective assistance of counsel for failure to timely object to this and other testimony. After hearing evidence, the trial court found that counsel was not ineffective, and we affirmed. Upon further review, the supreme court reversed and remanded for a new trial after concluding:
We note that the admission of [the expert's] testimony concerning the truthfulness of [the complainant’s] testimony is in violation of our holding in State v. Myers, 382 N.W.2d 91, 97-98 (Iowa 1986). However, we choose not to rest our conclusions in the present case upon the Myers violation alone.
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The State’s suggestion that Tracy's trial counsel may have intentionally allowed [the expert] to testify so as to cross-examine him regarding a seemingly inconsistent statement in his report ... is simply not tenable. The collective prejudicial impact of [the expert’s] testimony in conjunction with that given by the others clearly outweighs any favorable testimony that could reasonably have been anticipated in the course of [the expert’s] cross-examination. Finally, we conclude that any argument that defense counsel failed to object so as to avoid calling the jury’s attention to [the expert’s] unfavorable testimony is unrea*531sonable in light of our position that the mere admission of such evidence is reversible error; this proposition applies with equal force to the hearsay testimony given_ In short, we find that Tracy’s counsel failed to perform an essential duty in failing to make a timely objection to the testimony indicated above.
In the instant case, the State advances arguments similar to those advanced by the State in Tracy. Here the State claims defense counsel’s election not to object to the social worker’s testimony was a strategic decision. It claims defense counsel purposely permitted the social worker to testify about the complainants’ truthfulness and credibility so that defense counsel could discredit this same testimony during cross-examination. In addition, the State advances defense counsel’s testimony that, as a general rule, she refrains from lodging objections as further justification for her claimed trial strategy in the present case. We find these contentions to be without merit just as the supreme court has done before us.
We find defense counsel’s contention that objecting to the opinion testimony would have detracted from her strategy to be entirely without merit. We agree with the district court that defense counsel’s claimed trial strategy did not require counsel to remain mute when an opinion regarding the complainants’ truthfulness was being elicited. This is particularly true in light of the fact that the only evidence the State offered to connect the defendant to the alleged sexual abuse was the testimony of the two complainants.
With the credibility and truthfulness of the alleged victims being the main point upon which this case revolved, a reasonable probability existed that but for counsel’s unprofessional errors, the result of the proceeding would have been different. “A reasonable probability is a probability sufficient to undermine confidence in the outcome.” Tracy, 482 N.W.2d at 680 (citing State v. Hildebrant, 405 N.W.2d 839, 841 (Iowa 1987)). Specifically, the defendant was prejudiced at trial when the social worker informed the jury that the two complainants “are telling the truth and that they are credible.” This conclusion is solidified by the fact that the State elicited this opinion immediately prior to calling the complainants to the witness stand.
Because defense counsel’s failure to object to this opinion testimony was deficient and resulted in prejudice to the defendant, we affirm the district court’s ruling granting the defendant’s application for postcon-viction relief.
AFFIRMED.
OXBERGER, C.J., concurs.
HABHAB, J., dissents and files an opinion.