The aim of this study - assessment of knowledge and awareness of drug addicts on the epidemiology, treatment and prevention of hepatitis B and C infections and AIDS in order to improve preventive measures. In total 64 patients were interviewed: 30 women and 34 men. The method of collecting material: questionnaires, interviews with the help of specially designed questionnaires. The method was based on questionnaire of a public survey conducted by specialists General Department of Federal Service for Execution of Punishment (GUFSIN) in St. Petersburg and Leningrad Region, as well as the Biomedical Center of St. Petersburg in cooperation with Yale University, USA. The age distribution of respondents was uneven. The proportion of young people under the age of 25 years was the lowest - 10.9% of patients, cases aged 25-34 years - 46.8%, 35 years and older ones - 42.2. Such a distribution by age, in general, reflects the age structure of addiction incidence rate in Moscow. The results of the survey patients in the Narcological Clinical Hospital № 17 for the assessment of knowledge on the epidemiology, treatment and prevention of hepatitis B and C, HIV infection and AIDS have shown that they are aware of the epidemiology and treatment of these infections, while women were more knowledgeable than men. At the same time, the respondents showed little knowledge of these issues and little interest in treatment that most likely comes from misunderstanding of risk of these diseases. This ultimately leads to higher values of these patients (not interested in their health and the health of others and underestimating the risk of disease) as a potential sources of infection. When checking the knowledge about the transmission of hepatitis B, C and HIV viruses the highest awareness was observed in respect of HIV infection and AIDS, much less patients know about hepatitis C, and even less - about hepatitis B. Consequently, inadequate awareness (in all aspects of the problems) of the threat posed by the HIV epidemic, AIDS and hepatitis B and C, proves to be another of the many factors contributing to the high incidence of hepatitis and HIV infection among drug addicts. Thus, our results also suggest the importance of sanitation-educational work among the addicted patients and the need for the delivery accessible and fascinating instruction booklet highlighting the key issues of epidemiology, treatment and prevention HIV- infection, hepatitis B and C. Each patient should be provided with a such booklet. It is necessary to develop a test control, allowing to catch the interest and focus on critical issues of prevention and treatment of tuberculosis, HIV infection and parenteral hepatitis, if possible, from time to time to lecture.