The cases of drug trafficking and the children involved in the crimes hiked in the past few years. Considering this fact a descriptive study was undertaken by the investigator to assess the knowledge and attitude regarding ill effects of substance abuse among adolescent boys. The other objectives of the study were knowledge and attitude of adolescent boys, to correlate knowledge with attitude, to associate knowledge and attitude with selected demographic variables of adolescent boys and to develop a self instructional booklet regarding ill effects of substance abuse. Multi stage random sampling was done to select 100 samples. Data collection was done through structured knowledge questionnaire to assess knowledge regarding ill effects of substance abuse and attitude was assessed using five point Likert scale. Following the collection of data the investigator distributed self instructional booklet regarding ill effects of substance abuse. Regarding the results, about 89% of adolescent boys possessed moderate knowledge, 11% of adolescent boys had inadequate knowledge and none of them possessed adequate knowledge regarding ill effects of substance abuse. Considering the attitude, about 83% of adolescent boys had moderately favourable attitude, and 13% had favourable attitude and only 4% had unfavourable attitude towards ill effects of substance abuse. With regard to correlation there was a negative correlation between knowledge and attitude regarding ill effects of substance abuse. Considering the association there was no significant association between knowledge as well as attitude with selected demographic variables.