It has recently been claimed that UK medical students from ethnic minorities perform less well than White students in final undergraduate examinations and that this results from discrimination in clinical examinations. In this paper the authors examine the performance of students in two prospective studies of 1981 and 1986 entrants to London medical schools taking finals in 1986, 1987, 1991 and 1992. Overall, 18.2% of students in the survey failed one or more examinations at finals. UK ethnic minority students were 2.09 times more likely to fail one or more examinations than were UK White students. Male students were also 1.65 times more likely to fail an examination than female students. More detailed analysis of individual marks confirmed that UK ethnic minority students performed less well than UK White students, although non-UK ethnic minority students performed better than UK White students. The difference between UK White and ethnic minority students could not be explained by differences in educational achievement, study habits or clinical experience. The poorer performance of UK ethnic minority students extended across multiple-choice questions (MCQ), essay, clinical and oral examinations. Ethnic minority students performed particularly poorly on examinations in medicine and surgery as compared with pathology and clinical pharmacology. Although UK-born ethnic minority students perform less well in final examinations than UK White students, this is unlikely to be explained by racial discrimination as the difference is present in MCQ examinations marked by machine and as non-UK ethnic minority students perform better than UK White students. The cause of the difference in performance is therefore not clear and requires further study.