To determine the extent of occupational exposure to blood in medical students, details of the circumstances surrounding the incidents and the subsequent experiences of the student.Prospective cohort study.Tygerberg Hospital, the Health Sciences Faculty of the University of Stellenbosch during a 15-week period from 4 February to 19 May 2002.One hundred and thirty-six student interns (SIs), i.e. final-year medical students.All Sis received a questionnaire and a letter motivating them to participate in the study and explaining the procedure. Regular class meetings enabled continuous motivation and ongoing update. In the case of an incident during the 15-week period, the SI filled in the form and placed it in a sealed drop-off box.Specific focus on the preceding events and the situation in which the incidents occurred (department, time of day, procedure performed, and whether the student was on call), exposure to HIV (patient's retroviral status), use of post-exposure prophylaxis (PEP) (whether used, when initiated), and the consequences of the exposure (emotional, on sexual behaviour during the window period, and on career choice).During the 15-week period, 19 incidents were reported; the majority occurred while students were on call, almost half occurred after hours, and a disproportionate number occurred in three departments.Occupational blood exposure is a very real problem and poses a significant risk. SI suggestions should be considered in improving the prevention and management of such incidents.