The objective of this study was to assess the effectiveness of undergraduate training in knee aspiration and to determine the impact this had on subsequent postgraduate clinical practice. This paper is a cohort study of undergraduate training with a cross-sectional questionnaire study of postgraduate practice. The study was held at the University of Cambridge and NHS hospitals in the Eastern Region Postgraduate Deanery (England). The main outcome measures are the undergraduate competence in practical skills in a simulated setting and the differences in postgraduate practice with or without prior undergraduate training in knee aspiration. Implementing an undergraduate training programme in knee aspiration resulted in student competence in this skill. Undergraduate teaching of knee aspiration also improved postgraduate clinical practice, significantly increasing trainee doctor confidence and also increasing the frequency with which knee aspiration was undertaken. Postgraduate reinforcement of learning was identified as an additional requirement. Undergraduate teaching of knee aspiration not only results in competent performance in end of course assessments but also improves postgraduate confidence that potentially translates into improved clinical practice.