Among school leavers applying to study medicine in the United Kingdom a majority offer General Certificate of Education, Advanced Level (A-level) examinations as part of the assessment of academic ability. At the time of application, up to 9 months before completing A-level studies, schools are requested to predict the final grades likely to be achieved by the applicant. A total of 5054 A-level predictions from 1661 applicants to a single medical school were compared with the results achieved. Predicted and achieved grades were both high with 93% of predicted grades being A or B. Over half the predictions were correct, with 41% of predictions above achieved grades and only 7% below achieved grade. Independent and selective schools predicted higher grades than comprehensive schools and sixth form colleges, and their pupils were more likely to achieve the entrance requirements. A-level predictions for medical school applicants are a strong predictor of achievement and should continue to be regarded as a useful part of the selection process.