BACKGROUND: Smoking and snuff habits among medical students are of interest because they may reflect the attitude to smoking and snuff among future doctors, but few longitudinal studies have been performed. MATERIAL AND METHOD: A standard questionnaire, developed by Statistics Norway, was handed out to all medical students at the University of Bergen during plenum lectures in the spring 2004 and 2006. The questionnaires were marked by personal codes to enable follow-up of smoking and snuff habits for each individual student during the study period. New questionnaires were sent by post to all students who did not respond after the initial handout. RESULTS: 799 medical students (89 %) responded in the spring 2004 and 789 students (84 %) in the spring 2006. The study revealed that 3 % of the students smoked regularly in 2004 and 1 % in 2006 and that 20 % were occasional smokers in 2004 and 18 in 2006. 15 % of the students were snuff users in 2004 and this had increased to 24 % in 2006. INTERPRETATION: A decrease was observed in both daily and occasional smokers among medical students in Bergen during the two-year study period. However, the frequency of snuff users increased. The frequency of regular smokers is low, but the number of occasional smokers is higher than in the general population of the same age.