BACKGROUND Self-medication results in wastage of resources, increases resistance of pathogens and generally causes serious health hazards such as adverse drug reactions, prolonged suffering and drug dependence. This study was undertaken to determine the reasons for self-medication and the pattern of self-medication among medical students. METHODS This cross-sectional descriptive study was conducted at the K.S. Hegde Medical Academy, Mangalore. The participants were medical students from first to final year. Medical students were selected through convenience sampling. The data was collected using a pre-tested semi-structured questionnaire. The data was analysed using SPSS version 16 and the results expressed as proportions. RESULTS A total of 200 students, 121 (60.5%) female and 79 (39.5%) male, were included in the study. Of the medical students surveyed, self-medication was reported among 92%. The respondents who used self-medication found it to be time- saving in providing relief from minor ailments. The most common ailments for which self-medication were used were: the common cold (69%), fever (63%) and headache (60%). The students consulted their textbooks (39%) and seniors or classmates (38%) for the medications. Antipyretics (71%), analgesics (65%), antihistamines (37%) and antibiotics (34%) were the most common self- medicated drugs. Of the respondents, 33% were unaware of the adverse effects of the medication and 5% had experienced adverse reactions. The majority (64%) of students advised medications to others, more often to family and friends. CONCLUSIONS The prevalence of self-medication among medical students is high, facilitated by the easy availability of drugs and information from textbooks or seniors. A significant number of students are unaware of the adverse effects of the medication that they themselves take and suggest to others. Therefore, potential problems of self-medication should be emphasised to the students.