The debate around which factors drive medical students' learning is ongoing and controversial. What is the influence of an assessment's weighting on the motivation of students to study the particular subject? One medical school in London is in a unique position to investigate this question. At our institution, the weighting of Anatomy within the overall scheme of assessment has changed twice in recent years, a trend of increased weighting. This enabled a comparative investigation into the effect these changes have had on the students' motivation to learn Anatomy. A five-point Likert-scale questionnaire survey was used to evaluate students. A section within a broad survey of Anatomy teaching and learning at our institution was dedicated to the evaluation of the amount of weighting Anatomy received within the assessment structure and the effect this had on students' motivation toward learning the subject. Increasing Anatomy's weighting within the scheme of assessment produced a dramatic increasing trend toward students' motivation to learn Anatomy. The weighting of Anatomy has a profound effect on students' motivation to learn it. Although multifactorial and complex in nature, medical students' self-reported drive to study a subject is directly influenced by the weighting of the subject in the overall scheme of assessment. (Contains 2 tables and 2 figures.)