There is controversy about the influence of psychiatric clerkships on medical students' attitudes to psychiatry. In general, studies in developed countries have found a short-lasting improvement in attitudes to psychiatry after a psychiatric clerkship. The present study was designed to measure changes in medical students' attitudes following a psychiatric clerkship in a developing country. Medical students from the Faculty of Medicine, University of Chile were interviewed before and after a psychiatric clerkship using a translation into Spanish of an attitude-to-psychiatry questionnaire used previously in the UK. The results were similar to those reported from developed countries. There was a marked early improvement in students' attitudes following their psychiatric clerkship which gradually faded over 3 years. There is scope for improvement in psychiatric undergraduate medical teaching in Chile and this might help to make more lasting improvements in attitudes to psychiatry among medical students.