BACKGROUND There are scant studies on the prevalence and determinants of tobacco smoking among 1st year university students in Iran. We aim to determine the prevalence of substance abuse and identify factors related with tobacco smoking in 1st year students of Qazvin University of Medical Sciences (QUMS). METHODS A self-administered questionnaire was used to collect information on sociodemographic, cigarette smoking, hookah smoking, and related risk factors among 521 1st year students in QUMS between January and February 2014. We used logistic regression to determine factors associated with substance abuse among students. RESULTS The descriptive statistics indicated that the prevalence of lifetime cigarette and hookah smoking was 8.6% (confidence interval [CI] 95%: 6.5-11.4) and 35.5% (CI 95%: 31.5-39.7), respectively. After adjustment for other factors, being male, the presence of any smoker in the family and having smoker friends were factors associated with cigarette and hookah smoking among students. Our findings also revealed the co-occurrence of risk-taking behaviors among students. CONCLUSIONS Our study showed considerably low prevalence of tobacco smoking among 1st year students. Longitudinal studies are necessary to approve the observed results of this study and thus allow for a certain generalization of the observations.