The topic of the thesis is "SELF-DEFENSE, EXCESSIVE SELF-DEFENSE, AND EXTREME NECESSITY IN CROATIAN CRIMINAL LAW AND PRACTICE." The thesis is divided into six main chapters: 1. Introduction, 2. Self-defense, 3. Excessive self-defense, 4. Examples of self-defense and excessive self-defense, 5. Extreme necessity, 6. Conclusion. In the introduction, I described the reasons for choosing this topic, explained the concept of unlawfulness, and mentioned all the reasons for excluding unlawfulness, as I believe these are essential concepts for understanding the institutes of self-defense and extreme necessity. In the chapter on self-defense, I first mentioned some general aspects of it and cited the article of our legislator that regulates it. Then, I briefly went through the historical development of the institute and highlighted the basic differences between regulations in continental and Anglo-Saxon legal systems. After that, I explained the elements of self-defense and highlighted the importance of proportionality and simultaneity as conditions for self-defense. I also explained the institute of necessary assistance as a subtype of self-defense and the reasons for excluding the right to self-defense and the reasons for limiting self-defense. In the chapter on excessive self-defense, I first generally described how it is challenging in practice to assess whether it is excessive or not, and then described the types of excessive self-defense, which are: intensive excess, extensive excess, and excessive self-defense due to strong provocation or fright caused by the attack. Then, I supported the theory of self-defense and its excess with two detailed examples from practice in a new chapter. In the chapter on extreme necessity, I first generally described the institute, then explained the monistic and differentiating theory of extreme necessity, and the reflection of these theories on the development of the institute in the Republic of Croatia. After that, I described the two basic types of extreme necessity, which are; justifying extreme necessity and excusing extreme necessity, and at the end of that chapter, I detailed two examples from practice. In the conclusion, I gave my perspective on the importance of the mentioned institutes, and I believe that these are institutes about which even laypeople should know the basics, so they can at any moment know the possibilities of protecting their rights in accordance with the law.