The object of the present scientific research refers to the problem of the proportionality of the defense with the seriousness of the attack in the case of self-defense. It is shown that limiting the right to defense based on the criterion of proportionality excludes, in certain cases, the possibility of invoking self-defense. Likewise, it is shown that in the context of evaluating the proportionality of the defense with the seriousness of the attack, the interpreter will not have to limit himself to balancing the social values confronted, making them detached from any other type of element, but will be obliged to take into account both the defensive and offensives means used, the circumstances and conditions of the production of the attack and defense, the physical and mental characteristics of the attacker and the defender, as well as other elements that can help to clarify that question.