Health professional education (HPE) has grown as a field of research, with an increasing number of publications since the 1990s. Interprofessional education is a specific area of growth with ongoing debate in the literature, at least in part due to the challenges that exist in implementation, and further research is needed to inform ongoing practice. Participant recruitment is a major challenge, and poor participation rates lead to bias and a failure to demonstrate outcomes. There is a lack of information about why students decline to participate in research to inform and improve education. Motivation for volunteerism in other contexts and recruitment of human participants in other types of research are examined as a way to understand the likely motivations of student participants. Disincentives to participate include time commitment, survey fatigue and a poor understanding of the value of HPE research and the processes involved. The ethical considerations for teacher-researchers add another layer of complexity to recruitment. A multifaceted approach, involving all stakeholders and targeting known influences, is needed to improve recruitment in health professional education research, and clear communication of the research rationale and its potential impact on curriculum design is essential. Explicit communication and adequate information to allow informed student choice are also required, while improved literacy in HPE research may provide students with a better basis for decision making when considering participation. In addition, partnership and student co-design could be a mechanism for more meaningful engagement.