Objectives: In spite of some evidence suggesting that alcohol and drug use has been increasing among youths and students, no comprehensive and systematic study on the issue has been done yet and there have been some contradictory estimations of drug and alcohol use among students. This article aims to provide reliable data on the prevalence of drug and alcohol among university students. Method: The data were collected in a comprehensive survey study on drug and alcohol use among non-medical state universities in Iran in 2002-2003 educational year. In this survey a representative sample including 2531 male and female students of 21 state universities from all over the country answered to a self-report questionnaire. The respondents were selected by PPS (Probability Proportionate to Size) sampling method. Findings & Results: 60% of the respondents observed opium and about 20% observed crack and heroin directly, while new drugs were observed only by 5% and less. 20% and 10% has the experience of using, respectively, alcohol and opium at least once in their life time. However, the percentage of drug addicts among university students was relatively low and it was estimated at most about 1%. Traditional drugs and alcohol were considerably available for the students. About 42 percent reported they had been at least once in a place where some people used drug. Nonetheless, the percentage of drug users and addicts is relatively low. This can be seen as a support for demand reduction programs. Among those reported using alcohol and drugs, respectively 40 and 33 percent reported their first use had been before their entrance to university. This suggests that demand reduction programs are required to begin from high school and even earlier. The data also revealed that most opium users used it individually and without their family awareness, while alcohol users used it in friendly and family occasions more often. About half of them expressed that their family were aware of their alcohol use. This inferred that alcohol use is more commonly accepted among some families, particularly, those with higher socio-economic status. It was also found that the pattern of drug and alcohol use varies with regard to age, gender, socio-economic status, and ethnicity. Female students used alcohol and drugs considerably less than male students, however, gender differences in alcohol use was smaller than that in drug use. Regarding the age, elder students used drugs and alcohol more than younger students. Socio-economic status of the respondents’ family was positively related to alcohol use while its relation with drug use was negative. With regard to ethnicity, some differences observed among different ethnicities. In general those identified themselves as Persian and Turkish reported less drugs and alcohol use. Kurd and Lore students had the highest level of both drug and alcohol use.