delivered the opinion of the Court.
The defendant, Dennis Joseph Montoya, appeals the sentences imposed for his convictions of attempted manslaughter1 and first-degree *113assault.2 The primary issue on appeal is whether the statutory penalty for first-degree assault, in the context of the present statutory scheme, is constitutional when applied to defendants who can establish that they acted in the “heat of passion.”
At T.00 a.m. on December 26, 1975, the defendant returned home from a two-day drinking episode. The defendant found his apartment door locked and ordered his wife to let him into their home. He shouted that he would kill anyone that he found in the apartment with his wife. At that time, the defendant’s wife and Joseph Cortez were in bed together and both were nude. Mrs. Montoya quickly shoved her still-naked lover into a closet. The defendant, meanwhile, had broken a window on the door and entered the apartment. Soon thereafter, he discovered Cortez in the closet and shot him in the chest with a handgun. Cortez was able to run from the apartment and obtain medical attention. He survived the attack.
Trial to a jury resulted in the defendant’s convictions for attempted manslaughter and first-degree assault. We reverse the defendant’s sentences and remand for sentencing not inconsistent with this opinion.
The defendant relies upon our decision in People v. Bramlett, 194 Colo. 205, 573 P.2d 94 (1977), cert. denied, 435 U.S. 956, 98 S.Ct. 1590, 55 L.Ed.2d 808 (1978), for his contention that the penalty imposed for his first-degree assault conviction violated his right to equal protection of the law. U.S.Const., Amend. XIV. He contends that a person who acts under the “heat of passion” cannot constitutionally be subjected to a greater penalty when he causes serious bodily injury than he would when he caused the death of his victim. We agree.
The legislature is entitled to establish more severe penalties for acts which it believes have greater social impact and more grave consequences. People v. Czajkowski, 193 Colo. 352, 568 P.2d 23 (1977). Harsher penalties for crimes committed under different circumstances than those which accompany the commission of other crimes do not violate equal protection guarantees if the classification is rationally based upon the variety of evil proscribed. The classification, however, must reflect substantial differences having a reasonable relationship to the persons involved and the public purposes sought to be achieved. People v. Bramlett, supra; People v. Hulse, 192 Colo. 302, 557 P.2d 1205 (1976); People v. Calvaresi, 188 Colo. 277, 534 P.2d 316 (1975). Where two statutes provide disparate penalties for similar criminal conduct, equal protection guarantees are violated. People v. Bramlett, supra; People v. McKenzie, 169 Colo. 521, 458 P.2d 232 (1969).
Colorado’s first-degree assault statute, section 18-3-202, C.R.S. 1973, provides, in pertinent part:
*114“(1) A person commits the crime of assault in the first degree if:
“(a) With intent to cause serious bodily injury to another person, he causes serious bodily injury to any person by means of a deadly weapon.” First-degree assault is a class three felony which carries a minimum sentence of five years and a maximum sentence of forty years’ imprisonment in the state penitentiary. Section 18-1-105(1), C.R.S. 1973.
The manslaughter statute, section 18-3-104(l)(c), C.R.S.- 1973, provides:
“(1) A person commits the crime of manslaughter if:
“(c) With intent to cause the death of a person other than himself, he causes the death of that person, or of another person, under circumstances where the act causing the death was performed, without premeditation, upon a sudden heat of passion caused by a serious and highly provoking act, affecting the person killing sufficiently to excite an irresistible passion in a reasonable person; but if between the provocation and the killing there is an interval sufficient for the voice of reason and humanity to be heard, the killing is murder.”
Under the manslaughter statute, a person who intentionally causes the death of another in the “heat of passion” is guilty of a class four felony and is subject to imprisonment for one to ten years. Section 18-1-105(1), C.R.S. 1973. A person who intentionally causes serious bodily injury under “heat of passion,” however, is subject to conviction for first-degree assault and imprisonment for a term of five to forty years. Thus, the offender who acts with the less culpable intent and who causes the less grievous result receives the greater penalty. Such an unreasonably structured legislative scheme is constitutionally infirm. People v. Bramlett, supra.
In People v. Czajkowski, supra, and People v. Hulse, supra, we held that crimes which were readily distinguishable on the basis of their elements did not violate equal protection rights if they imposed disparate penalties. We are unable to so distinguish the crimes in this case. If the person assaulted in this case had died, the jury would have returned a manslaughter conviction, since it did find the defendant guilty of attempted manslaughter. The defendant’s first-degree assault conviction, therefore, rested in large part upon the fortuity that his victim survived the incident. Under the unique factual circumstances in this case, and as the disparate statutory penalties were applied, the defendant was denied the *115equal protection of law by the application of the statutory penalty for first-degree assault.3
The limited nature of our decision in this case and in People v. Bramlett, supra, cannot be overemphasized.4 In both cases, the relevant statutes imposed a greater penalty for a lesser offense where the crimes charged did not contain rationally distinguishable elements. In this case, we hold that a person charged with first-degree assault, who can establish that he acted in “heat of passion,” is constitutionally protected against receiving a greater penalty than he could have received had he caused the death of his victim.5
Accordingly, the sentences of the defendant are vacated, and the cause is remanded to the trial court with directions to resentence the defendant in a manner not inconsistent with the directives contained in this opinion.
MR. JUSTICE GROVES and MR. JUSTICE LEE do not participate.