This cross-sectional study investigated smoking patterns and predictors among Vietnamese medical students. In total, 4720 medical students from 3 universities, each located in South, Central, and North Vietnam, were interviewed using an adapted Global Youth Tobacco Survey Questionnaire. Ideas on smoking behavior and tobacco control derived from group discussions with students and from unstructured interviews with student managers and university directors. Overall, the current smoking rate was 25.0% and dominant in men at 43.7%. Most started smoking when just entering university (18 +/- 3.3 years). Male students from the central region had the highest smoking rate (35.1%), whereas their northern counterparts had the greatest smoking magnitude: age of smoking initiation (18.6 +/- 3.5), number of cigarettes per day (4.4 +/- 4.5), number of smoking days per month (16.5 +/- 11.6), and proportion of smoking cost among total expenses per month (10.9% +/- 11.9%). Smoking tended to increase across academic years, being highest in years 5 to 6 (35.0%). In contrast, the practice of ever quitting and the intention of quitting tended to decline from years 1-2 to years 5-6 (from 82.2% to 71.5%, P < .05, and from 70.8% to 51.5%, P < .001, respectively). Positive attitudes toward smoking (odds ratio = 1.4, P < .05), negative beliefs on hazards of smoking (odds ratio = 1.7), and daily exposure to family smokers (odds ratio = 2.0, P < .05) and to social smokers (odds ratio = 4.5, P < .05) were main predictors of smoking. Qualitative results suggest that nonsmoking university regulations played a critical role in tobacco control among medical students. Nonsmoking regulations and penalties for students who smoke need to be formulated at medical universities. The message that medical students must make a nonsmoking role model for community should be systematically promoted.