This study aimed to provide evidence to guide decisions on the type and timing of assessments in a graduate medical programme, by identifying whether students from particular degree backgrounds face greater difficulty in satisfying the current assessment requirements. We examined the performance rank of students in three types of assessments and also calculated the relative risk of failure in the summative assessments for four cohorts over all four years of a four-year graduate medical programme. Our findings suggest that early summative assessment may disadvantage the very students who create the diversity that the faculty values, particularly if methods such as Single Best Answer questions are used, unless students are provided with additional support in bridging their knowledge gap. Use of assessment methods such as Modified Essay Questions and Objective Structured Clinical Examinations appears to be more justifiable on educational grounds. (Contains 4 tables and 1 figure.)