Medical student wastage leads to adverse emotional and social consequences for individual students and financial difficulties and morale problems for medical schools. This study retrospectively assessed the records of all students at Leeds School of Medicine who left the course prematurely between 1983 and 1992. The demographic data of the leavers were compared with those of all students entering the school during the 10 years studied. A-level examination choices and results of the leavers were compared with those of a control group of all students who entered the school in 1990. The attrition rate over the 10 years was 14% (283 students), with more males than females leaving. Fewer mature students than expected left the course. More leavers had A-level physics and lacked A-level biology compared with the control group. The leavers were academically less able than the controls. Fifty-three per cent of leavers were asked to withdraw from the course for academic reasons; the rest left voluntarily. Thirty per cent had personal problems, 9% had a combination of academic and personal problems and 8% had health problems (psychological difficulties were the commonest). Seventy-one per cent of leavers entered another degree course; science degrees were the most popular. Reasons for medical student wastage and possible solutions are discussed.