The article considers medical and pedagogical prevention of deviant behavior of adolescents from dysfunctional families in conditions of rural school, related to the need of strengthening targeted joint interaction of medical and pedagogical institutions. The description and results of testing of diagnostic tools used to establish severity of deviant behavior of children in a selected group is discussed. The interaction of medical and educational institutions in preventing deviant behavior of adolescents from dysfunctional families in rural school is of key importance for combating prevalence of drug addiction, tobacco smoking, alcohol abuse and psychoactive substances consumption, and contributing to physical and mental health promotion of younger generation, development of healthy lifestyle. The study was organized to cover cognitive, behavioral, affective and value-motivational components. The qualitative characteristics of levels of severity of deviant behavior of adolescents from dysfunctional families were developed and proposed for practice application.