Objective To review published examples of public involvement in research design, to synthesise the contributions made by members of the public, as well as the identified barriers, tensions and facilitating strategies. Design Systematic literature search and narrative review. Findings Seven papers were identified covering the following topics: breast-feeding, antiretroviral and nutrition interventions; paediatric resuscitation; exercise and cognitive behavioural therapy; hormone replacement therapy and breast cancer; stroke; and parents’ experiences of having a pre-term baby. Six papers reported public involvement in the development of a clinical trial, while one reported public involvement in the development of a mixed methods study. Group meetings were the most common method of public involvement. Contributions that members of the public made to research design were: review of consent procedures and patient information sheets; outcome suggestions; review of acceptability of data collection procedures; and recommendations on the timing of potential participants into the study and the timing of follow-up. Numerous barriers, tensions and facilitating strategies were identified. Conclusions The issues raised here should assist researchers in developing research proposals with members of the public. Substantive and methodological directions for further research on the impact of public involvement in research design are set out.