In the present study, medical students' research activity was assessed. All of the 545 medical students at the University of Helsinki in spring term 1997 were provided with a structured, self-administered questionnaire. The questions concerned participation in, motives for and productivity of research work. Additionally, factors obstructing research work and the most valued quality of the supervisor were examined. The questionnaire was returned by 298 (5%), students. Ninety-one (31%) students reported having been involved with extracurricular research work. Male students were significantly more often involved in scientific research (p = 0.001) and had also published more than female students (p = 0.05). Scientific interest and a desirefor residency were equally important motives for involvement in research. Scientific competence was regarded as the most important quality of the supervisor and the main obstacle to carrying out research work was qualitative and/or quantitative insufficiency in supervising. Medical students should be encouraged to carry out research work, because they thus learn critical and logical thinking. They should also be given all the credit for the work they have done.