On the basis of a questionnaire on smoking behaviour, knowledge and attitudes administered to medical students in the University of Malaya in July 1987, the prevalence of smoking was found to be low (10%) among medical students. Smokers and non-smokers were equally well informed about common smoking complications. Most students, irrespective of smoking status, felt that they would as future doctors, often advise sick smokers against smoking. In contrast, less than half would do so for healthy smokers who do not themselves raise the question of smoking. The students' personal smoking behaviour also influenced their view of their professional role. Appropriate values, attitudes and a preventive approach towards smoking need to be further developed in the medical students' thinking and behaviour.