Background: UK-trained medical students and doctors from minority ethnic groups underperform academically. It is unclear why this problem exists, which makes it dif?cult to know how to address it. Aim: To investigate whether demographic and psychological factors mediate the relationship between ethnicity and ?nal examination scores. Sample: Two consecutive cohorts of Year 5 (?nal year) UCL Medical School students ("n" = 703; 51% minority ethnic). A total of 587 (83%) had previously completed a questionnaire in Year 3. Methods: Participants were administered a questionnaire in 2005 and 2006 that included a short version of the NEO-PI-R, the Study Process Questionnaire, and the General Health Questionnaire (GHQ) as well as socio-demographic measures. Participants were then followed up to ?nal year (2007-2010). White and minority ethnic students' questionnaire responses and ?nal examination grades were compared using univariate tests. The effect of ethnicity on ?nal year grades after taking into account the questionnaire variables was calculated using hierarchical multiple linear regression. Results. Univariate ethnic differences were found on age, personality, learning styles, living at home, ?rst language, parental factors, and prior education. Minority ethnic students had lower ?nal exam scores, were more likely to fail, and less likely to achieve a merit or distinction in ?nals. Multivariate analyses showed ethnicity predicted ?nal exam scores even after taking into account questionnaire factors. Conclusions: Ethnic differences in the ?nal year performance of two cohorts of UCL medical students were not due to differences in psychological or demographic factors, which suggests alternative explanations are responsible for the ethnic attainment gap in medicine. (Contains 8 tables and 2 figures.)