A hypothetical model is developed to examine factors that influence achievement for graduate-entry medical students in their third year of university studies. Nine latent variables investigated consist of the students’ background, previous successes with their previous studies and their capacity to study graduate-entry medicine based on their pre-course aptitude and interview selection processes. The academic and clinical achievement of 99 graduate entry medical students are estimated by measuring their performance on multiple choice examination and objectively structured clinical evaluation (OSCE) test. The assessments were equated using Rasch scaling procedures and the model’s pathways were tested using Latent Variable Partial Least Square analysis (LVPLS). The study’s outcomes suggest the most significant predictors were student gender, their undergraduate grade point average scores and the type of undergraduate studies undertaken. Measures of aptitude and performance at interview involved in the pre-course selection process were not related to the final performance assessments.