In the present article a study of the self-defense is made in terms of its proportionality. Undoubtedly, this figure represents a limitation to the right to life and personal integrity, since reality and legislation have caused the injury to be justified or even to take of another person when they are attacked violently and without just cause. In this measure, the rejection of the attack requires a limit and that limit is proportionality, hence, if the attack and proportional defense is presented, by express legal mandate the criminal responsibility of the subject that defends itself is excluded. Hence, establishing the budgets of this permissive provision is important for full understanding.