*289OPINION OF THE COURT
PAPADAKOS, Justice.This appeal arises from an incident which occurred on October 19,1978, at which time Joseph Marzka was killed in the course of an argument with Appellant. Appellant was found guilty of murder of the first degree following a jury trial. He was sentenced to life imprisonment on July 31, 1979. Post-verdict motions were denied and this Court affirmed the judgment of sentence by per curiam opinion on April 10, 1980. Commonwealth v. Gass, 488 Pa. 512, 412 A.2d 882 (1980). Appellant then filed a Petition for Relief Under the Post Conviction Hearing Act,1 which, after an evidentiary hearing on August 21, 1981, was denied by the Court of Common Pleas on May 18, 1983. The Superior Court affirmed the denial of post-conviction relief on December 7, 1984. 339 Pa.Super. 615, 488 A.2d 1163. This appeal followed.
In this appeal, Appellant argues that 1) trial counsel was ineffective in failing to request a specific jury instruction that not guilty by reason of insanity was a possible verdict and an instruction as to the consequences of an acquittal by reason of insanity, and 2) trial counsel was ineffective for failing to object to the use of published articles during the cross-examination of Appellant’s expert witness, Dr. Thompson.
When confronted with claims of ineffectiveness, reviewing courts are governed by the standard as set forth by this Court in Commonwealth ex rel. Washington v. Maroney, 427 Pa. 599, 235 A.2d 349 (1967):
Our inquiry ceases and counsel’s assistance is deemed constitutionally effective once we are able to conclude that the particular course chosen by counsel had some reasonable basis designed to effectuate his client’s interests. The test is not whether other alternatives were more reasonable, employing a hindsight evaluation of the *290record. Although weigh the alternatives we must, the balance tips in favor of a finding of effective assistance as soon as it is determined that the trial counsel’s decision had any reasonable basis.
Id., 427 Pa. at 604, 235 A.2d at 352-53. We also noted in Maroney that:
... for relief to be granted, Appellant must demonstrate that counsel’s ineffectiveness worked to his prejudice....
Commonwealth ex rel. Washington v. Maroney, supra, 427 Pa. at 605 n. 8, 235 A.2d at 353 n. 8. See also, Commonwealth v. Bandy, 494 Pa. 244, 431 A.2d 240 (1981). The threshold inquiry is whether the issue/argument/tactic which counsel has foregone and which forms the basis for the assertion of ineffectiveness, was of arguable merit, Commonwealth v. Hubbard, 472 Pa. 259, 372 A.2d 687 (1977), for counsel cannot be considered ineffective for failure to assert a meritless claim. Commonwealth v. Stoyko, 504 Pa. 455, 475 A.2d 714 (1984). With the Maroney standard in mind, we proceed to Appellant’s specific claims of ineffectiveness.
Appellant first asserts that trial counsel was ineffective in failing to request a jury instruction that not guilty by reason of insanity was a possible verdict. Appellant relies on Commonwealth v. Mulgrew, 475 Pa. 271, 380 A.2d 349 (1977), for the proposition that once the issue of insanity has been raised, the court must state in its charge that “not guilty by reason of insanity” is a separate and distinct verdict in the case. Appellant further contends that the jury must be made aware of the meaning of such verdict, i.e., that it could mean that a defendant would be subject to commitment proceedings and psychiatric treatment.
Insanity was clearly at issue in Appellant's trial. In fact, Appellant’s defense rested solely upon a claim of insanity. The only witness presented by the defense was a psychiatrist. The Commonwealth’s evidence was undisputed. At the conclusion of the jury instruction, after the trial judge had recited the law on insanity generally and on homicide, he summarized the jury’s options as follows:
*291If you find the Defendant not guilty, that ends it. If you find him guilty, then you have to go on and specify the degree of the offense, if you find the Defendant guilty of murder in the first degree or the third degree or voluntary manslaughter or involuntary manslaughter. So there are five possible verdicts that you come in with. With our instructions, four types of homicide, and of course, one of not guilty. (Emphasis added.)
The court did not specifically state that not guilty by reason of insanity was a sixth possible verdict and, while the jury was aware of the insanity defense because it was raised at trial, the court’s charge did not cover it as a separate and distinct option. Despite the obvious error of the trial judge in failing to specify that a verdict of not guilty by reason of insanity was possible, trial counsel did not object to the omission.
In support of his contention that this omission constituted ineffectiveness of counsel, Appellant contends that the jury could conceivably have disbelieved all of the Commonwealth’s witnesses and found him “not guilty,” or that they might have believed both the Commonwealth’s witnesses and the defense psychiatrist and found him “not guilty by reason of insanity.” Since this was at least theoretically possible, Appellant argues that the instruction given was confusing and misleading and should reasonably have drawn objection from his trial counsel. We agree with Appellant that the instruction was legally incorrect, and that there is no apparent reason for trial counsel’s failure to object to this oversight. Thus, Appellant’s claim is of arguable merit.
Our next inquiry is whether there was a reasonable basis for trial counsel’s failure to request such an instruction and/or object to the charge given to the jury. Trial counsel testified at the P.C.H.A. hearing that he was aware of our decision in Mulgrew, supra, and its application to a verdict of not guilty by reason of insanity. However, he felt it was inapplicable because it was decided before the Mental Health Procedure Act of July 9, 1976, which repealed the *292Mental Health and Mental Retardation Act of 1966, which was applicable in Mulgrew. This conclusion was erroneous, and no doubt constitutes ineffective assistance.
On the facts of this case, counsel could have had no reasonable basis for failure to request a specific charge that not guilty by reason of insanity was a possible verdict, or to object when such charge was not given. Appellant’s sole defense was one of insanity. His actions in killing the victim were undisputed and he pled no justification other than his purported delusions. His entire defense consisted of psychiatric testimony. At no time did the defense argue that Appellant did not commit the crime. Quite to the contrary, it was all but admitted that Appellant had done the shooting (N.T. 9, 12, 14, closing arguments).
It is clear from the evidence that trial counsel could not reasonably have considered a separate “not guilty” verdict as one of the alternatives available to the jury. Trial counsel did not present any factual basis nor argument to the jury that Appellant was, or could be, “not guilty” in the sense that he did not shoot Mr. Marzka. Hence, a “not guilty” verdict was possible only if the jury accepted the defense of insanity. While it is true that the jury was instructed on the concept of insanity, they were not instructed that “not guilty by reason of insanity” was a possible verdict. We conclude that this omission worked to the prejudice of Appellant. In Mulgrew, supra, we held that when insanity is raised as a possible defense, the jury must be instructed concerning the possible psychiatric treatment and commitment of the defendant after return of a verdict of not guilty by reason of insanity. In so holding, we adopted the reasoning of the Circuit Court of Appeals for the District of Columbia in Lyles v. United States, 103 U.S.App.D.C. 22, 25, 254 F.2d 725, 728 (1957), cert. denied, 356 U.S. 961, 78 S.Ct. 997, 2 L.Ed.2d 1067 (1958), cert. denied, 362 U.S. 943, 80 S.Ct. 809, 4 L.Ed.2d 771 (1960), cert. denied, 368 U.S. 992, 82 S.Ct. 610, 7 L.Ed.2d 529 (1962), in stating why the jury should be made aware of the meaning of a not guilty by reason of insanity verdict. The *293Lyles court said that while the jury knows the meaning of a guilty and not guilty verdict, they do not know what a verdict of not guilty by reason of insanity means.
The issue of insanity having been fairly raised, the jury may return one of three verdicts, guilty, not guilty, or not guilty by reason of insanity____ It is common knowledge that a verdict of not guilty means that the prisoner goes free and that a verdict of guilty means that he is subject to such punishment as the court may impose. But a verdict of not guilty by reason of insanity has no such commonly understood meaning____ It means neither freedom nor punishment. It means the accused will be confined in a hospital for the mentally ill until the superintendent of such hospital certifies, and the court is satisfied, that such person has recovered his sanity and will not in the reasonable future be dangerous to himself or others. We think the jury has a right to know the meaning of this possible verdict as accurately as it knows by common knowledge the meaning of the other two possible verdicts.
Lyles at 25, 254 F.2d at 728.
In the instant case, not only was the meaning of a not guilty by reason of insanity verdict not explained to the jury, they were not even advised that it was a possible verdict. Based on the instruction that was given, we cannot assume that they understood that if they believed the insanity defense, they could find the Appellant not guilty by reason of insanity, when they were told that there were only five possible verdicts that they could reach. Nor can we speculate as to what the verdict would have been had they been properly instructed. The testimony of the defense psychiatrist was as follows:
I felt that at the time he was suffering from acute schizophrenia reaction and as a result of this was not aware of what he was doing and did not know the nature and quality of his acts at the time and also that in my opinion there was no way he could form premeditation to commit a crime. (N.T. 13-14, 5/25/79).
*294... I feel he was not capable of premeditation of murder____
I don’t feel he was capable of understanding the nature and quality of his act. (N.T. 25, 5/25/79).
We cannot find this testimony incredible as a matter of law. The Commonwealth did not present any psychiatric testimony. Thus, we find that Appellant has met his burden of proving that trial counsel’s ineffectiveness prejudiced his case. We reverse the judgment of sentence and remand the case for a new trial. Because of our disposition on the above issue, we need not consider the other allegations of error raised by Appellant.
Reversed and remanded for a new trial.
LARSEN, J., files a dissenting opinion joined by McDERMOTT, HUTCHINSON, JJ. HUTCHINSON, J., files a dissenting opinion joined McDERMOTT, J.. Post Conviction Hearing Act, Act of Jan. 25, 1966, P.L. 1580, § 1, 19 P.S. § 1180-1 et seq., reenacted as Act of May 13, 1982, No. 122, § 2, 42 Pa.C.S. § 9541 et seq.