This is a protocol for a Cochrane Review (Qualitative). The objectives are as follows:

The aim of this qualitative evidence synthesis is to explore the perceptions and experiences of potential and actual participants and trial recruiters to improve understanding of how interventions, strategies and processes of recruitment to RCTs potentially work for specific groups across different settings and contexts. The specific objectives of this review are:

to describe recruiters’ perceptions and experiences of recruiting participants to RCTs;

to describe potential and actual participants’ perceptions and experiences of recruitment to RCTs;

to describe why potential participants accept or decline participation in RCTs;

to explore the barriers and facilitators to participation in RCTs;

to explore how perceptions and experiences of trial recruitment interventions, strategies and processes influence the decision-making of potential and actual participants;

to explore to what extent the barriers and facilitators identified are addressed by interventions and strategies designed to improve recruitment evaluated in a previously published Cochrane review (Treweek 2010).