Objective Clinical trials have long been considered the ‘gold standard’ of research generated evidence in health care. Patient recruitment is an important determinant in the success of the trials, yet little focus is placed on the decision making process of patients towards recruitment. Our objective was to identify the key factors pertaining to patient participation in clinical trials, to better understand the identified low participation rate of patients in one clinical research facility within Ireland. Design Narrative literature review of studies focussing on factors which may act to facilitate or deter patient participation in clinical trials. Studies were identified from Medline, PubMed, Cochrane Library and CINAHL. Results Sixty-one studies were included in the narrative review: Forty-eight of these papers focused specifically on the patient's perspective of participating in clinical trials. The remaining thirteen related to carers, family and health care professional perspectives of participation. The primary factor influencing participation in clinical trials amongst patients was related to personal factors and these were collectively associated with obtaining a form of personal gain through participation. Cancer was identified as the leading disease entity included in clinical trials followed by HIV and cardiovascular disease. Conclusion The vast majority of literature relating to participation in clinical trials emanates predominantly from high income countries, with 63% originating from the USA. No studies for inclusion in this review were identified from low income or developing countries and therefore limits the generalizability of the influencing factors.