Adolescence characterize frequent psychical crisis which are result of biological development, looking for own identity, changes in family relation and many socio-cultural influences. Many of social, economic, other environmental factors make some changes in adolescent population. The main objective was finding how many adolescents had risk behavior and subsequences oftener sexual intercourse and aggressive behavior.

Research has done in Banjaluka's high schools, involved 202 adolescents age 18 (51 male, 151 female) which are separate in two groups. Adolescents who consumed psychoactive substances were in experimental group and control group involve adolescents who don’t use psychoactive substances. In research used risk behavior questionnaire Q-2000 (K.B. Kelly, 2000).

Out of total number of individuals in the study, 35,6% was cigarette smokers, 56,9% consumed alcohol, 20,2% consumed marijuana, and sexual intercourse 21,7% (75% used contraceptive methods). Adolescents which used alcohol oftener had sexual intercourse(27,8%, p= 0,026) than adolescents who don’t drink (13,8%), and 29,5% was aggressive in last year. Similar results was found in groups with marijuana and tobacco. Group which used marijuana 34,1% (p= 0,052) had sexual intercourse than group who don’t smoke cannabis (18,6%) and they were aggressive 41,8%. Group which used tobacco had sexual intercourse 34,7% (p=0,0017) than group nonsmokers (14,6%), and aggressive behavior 30,5%.

Adolescents are prone to abuse of psychoactive substances in developing countries. The consequence is higher risk behavior such as violence and promiscuity. Research will be conducted to develop preventive and educational programs in schools.