The topic of this paper is an institute of necessity. This paper explains and tries to approach the meaning of extreme necessity, its different shapes, how and when it was formed, what is the connection between extreme neccessity and neccesary defense, what are their similarities and differences, the content of extreme necessity, and a very important concept – the concept of danger. It also lists some examples in order to explain the concept of extreme necessity. The concept denotes the removal of concomitant danger that threatens, that could not be otherwise resolved. Extreme necessity is divided into two types according the differentiating theories, namely extreme necessity as a derogation and extreme necessity as the justification for a guilt. As for necessary defense and extreme necessity, the terms are similar. Necessary defense can be defined as the case of extreme necessity in which the danger occurs as a consequence of the unlawful attack and is eliminated if the attacker´s goods get attacked. Unlike that, in the case of extreme neccessity many different forms of danger can occur. If necessity occured, certain conditions must be met. These are the conditions relating to the state of danger, the elimination of danger and the relationship between the evil that is done and the harm threatened. The danger is a condition in which violation of legal goods is likely to occur, and to prevent the danger the actions that are justified and necessary can be taken. They will be justified when there was no other way for their elimination.