Summary. An investigation was undertaken to determine the factors influencing performance of medical students at the Faculty of Medicine, University of Kuwait. Data were collected for the first batch of 42 candidates who successfully passed the 7-year medical programme. Results showed high correlations between high-school admission grades and subsequent performance during the medical programme. Similar results were also obtained with English proficiency. A partial correlation controlling for English proficiency, however, showed a systematic decline in the magnitude of the correlations between high-school grades and performance during the medical programme. In fact the relationship between high-school GPA and clinical GPA was non-significant. A prominent influence of English proficiency on performance is indicated.