The article presents fanaticism as a universal phenomenon that can manifest itself in almost every sphere of human activity. It also describes the characteristics of the fanatism and distinguish the most important types of fanatism and their consequences. Most twentieth-century thinkers have come to the conclusion that, as part of the evolutionary process of developing scientific knowledge, fanaticism, in general, and religious fanaticism, in particular, will cease to exist. However, the reality shows that an increase in the number of educated people in a society does not have a direct effect on a decrease in the level of fanaticism in it. Fanaticism not only did not disappear, but also acquired a new status as a stable social tendency. That is why, the problem of fanaticism in the modern era has become particularly acute, since it is fanaticism, especially religious one, that underlies such a global threat to humanity as international terrorism. Ethnic conflicts just as clearly show how fanaticism plays a provocative role in fueling them. Due to this, the study of the phenomenon of fanaticism has not only theoretical, but also practical significance. Also, although many expressions of fanaticism are negative and destructive, some can be almost neutral or even positive.