Background: Substance abuse is an increasing public health problem. Use of tobacco, alcohol, and other substances is a global problem and affects many children and adolescents. Abuse of substances exposes the youth to several physical, psychological and social consequences. Objectives of the study were to determine the prevalence of substance abuse amongst high school students in selected schools of Bengaluru and to identify factors predisposing to substance abuse.Methods: Type of study was cross-sectional, study was done from November 2017 to January 2018, study subjects were high school students, sample size was 300, tool for study was structured questionnaire, descriptive analysis done using Microsoft Excel.Results: Out of 300 subjects 10% agreed that they have done abuse of substances. Most of them started it at age below 15 years. Most common reason to start was for fun.Conclusions: Substance abuse was present among high school students and most commonly abused substance was tobacco in the form of cigarettes and most common reason was for fun followed by peer pressure and low marks.