Context: Evidence supports the substitution of both clinical placement time and traditional educational activities with simulation-based education (SBE). However, lack of resources can be a barrier to SBE implementation. Peer simulation provides an alternative to simulated patient (SP)-based SBE by educating students to portray patient roles. This diversifies learning experiences for students using SBE and may decrease costs. Objectives: This study aimed to determine the impact of students portraying the roles of patients in a simulation-based learning environment (peer simulation) on learning outcomes in entry-level health care professional students. Methods: Seven databases were searched (from inception to 8 May 2019) using terms including 'peer simulation,' 'role-play' and 'simulated/standardised patient.' The studies included described a health care professional student SBE interaction involving peer simulation. Data were extracted by two independent investigators. Study quality was assessed using the Medical Education Research Study Quality Instrument (MERSQI) and Critical Appraisal Skills Programme (CASP). A descriptive analysis was completed and meta-analysis conducted in instances in which outcomes could be pooled. RESULTS: A total of 12 studies met the inclusion criteria. Constructs measured by the studies included communication, empathy, self-efficacy and confidence. Five randomised controlled trials compared peer simulation with the use of SPs and demonstrated greater or equivalent patient empathy gains in peer simulation. Meta-analysis determined no difference in communication capabilities between the two groups. Students perceived peer simulation as comparably valuable and frequently superior to other forms of learning. This review was unable to determine effective design features of peer simulation initiatives. Conclusions: Students were positive about peer simulation, but there has been limited evaluation of learning outcome attainment. Significant heterogeneity was observed; studies were diverse in design, outcome measures and the training provided for peer patients. Peer simulation positively influences student communication and development of patient empathy and offers an alternative to learning with SPs. Further rigorous research is required to understand the impact of peer simulation for a broader range of learning outcomes and to confirm the impact of this developing educational approach.