OBJECTIVE: This study aims at examining the patterns of substance use in Lebanon among an 'at risk' population, the university students. METHOD: A stratified cluster sample of 1,851 Students from two major universities was included in the study and the diagnostic interview schedule (version 3) was administered. Results: The prevalence of nicotine users in the sample was 18.3% and of ever consuming alcohol 49.4%. 2.1% of the sample were alcohol abusers and 2.4% alcohol dependents according to DSM-III criteria. For the remaining substances, tranquilizers were found to have the highest rate of ever use (10.2%), whereas heroin had the lowest rate (0.4%); the rates of abuse and dependence in these categories (other than alcohol and nicotine) following DSM-III criteria ranged from 0.1 to 0.8%. CONCLUSION: University students in Lebanon in this study have relatively low rates of use and abuse of substances but this might be changing.