Objective structured clinical examinations (OSCEs) are associated with high stress and anxiety levels, which could have a negative impact on student performance. Students frequently have no opportunity to practise OSCEs other than in the high-stakes examination itself. This study describes the design and implementation of a peer-run mock OSCE exam for medical students, and the feasibility, acceptability and perceived impact of this educational initiative. An OSCE training programme was designed by four fourth-year students. It involved the recruitment of 103 fourth-year tutors to facilitate the running and feedback of OSCE stations to 245 third-year medical students prior to their summative end-of-year exam. Tutees and tutors completed a questionnaire to assess the quality and perceptions of the benefits of this educational intervention. A total of 245 (85% of the year-3 group) tutee and 65 tutor surveys were completed over three evenings: 100 per cent of respondents classified the quality of the OSCE stations and resuscitation session as 'fantastic' or 'good'. The main themes from the tutee comments were: improved confidence and valued feedback. The main themes from the tutor comments were: motivation to continue with peer-assisted learning (PAL) projects and improved teaching skills. The peer-assisted mock OSCE improved tutee confidence and reduced the anxieties associated with OSCEs. Tutors gain valuable teaching skills. This PAL model is an acceptable, feasible and beneficial method of preparing students for this challenging style of health care examination.