The presented article is aimed to determine the share of information crimes in the structure of Russian extremist and terrorist criminality and, as a consequence, to propose effective methods of countering information crimes specifically for combating these crimes in general. The solution to this problem is implemented by applying statistical analysis of official data on criminality metrics supported by legal hermeneutics and sociological methods, combined with a historical approach to the subject. It is discovered that modifications in the legal regulation of information crimes in the Criminal code have largely led to changes in the number of registered extremist and terrorist crimes in general. The article reveals a significant share of information crimes in the structure of extremist criminality. In 2019, it decreased but still accounts for about a third of all extremist crimes. In the structure of terrorist criminality about every 10 terrorist crime is informational. The dissemination of illegal information during commission of information crimes is carried out through the Internet, while this is mostly relate to extremist crimes and only in a half cases to terrorist ones. Approximately in 75 % cases dissemination of extremist or terrorist information in Internet is carried out by people under the age of 30. The vast majority of all convicts are unemployed people without higher education. The system for preventing dissemination of extremist and terrorist information should be retargeted to improve the legal culture, including the value of each social group, as well as the culture of communication on the Internet.