Background: Peer-assisted learning (PAL) is increasingly used in medical education, and the benefits of this approach have been reported. Previous reviews have focused on the benefits of peer tutoring of junior students by senior students. Forms of PAL such as discussion groups and role-playing have been neglected, as have alternative teacher-learner configurations (e.g. same-level PAL) and the effects on other stakeholders, including clinician educators and patients. This review examines the benefits of same-level PAL for students, clinician educators and patients in pre-registration clinical medical education. Methods: Medline, PsycINFO, CINAHL and ERIC were searched in March 2014. A total of 1228 abstracts were retrieved for review; 64 full-text papers were assessed. Data were extracted from empirical studies describing a same-level PAL initiative in a clinical setting, focusing on effects beyond academic performance and student satisfaction. Qualitative thematic analysis was employed to identify types of PAL and to cluster the reported PAL effects. Results: Forty-three studies were included in the review. PAL activities were categorised into role-play, discussion, teaching and assessment. Only 50% of studies reported information beyond self-report and satisfaction with the PAL intervention. Benefits for students (including development of communication and professional skills) and clinician educators (developing less-used facilitation skills) were reported. Direct patient outcomes were not identified. Caveats to the use of PAL emerged, and guidelines for the use of PAL were perceived as useful. Conclusion: Many student-related benefits of PAL were identified. PAL contributes to the development of crucial skills required for a doctor in the workplace. Vertical integration of learning and teaching skills across the curriculum and tools such as feedback checklists may be required for successful PAL in the clinical environment. Benefits for patients and educators were poorly characterised within the included studies. Future work should evaluate the use of PAL with regards to student, clinician educator and patient outcomes.