Purpose of the article: With the call for patient-centred healthcare, designers and healthcare professionals collaborate increasingly, as both health and design researchers advocate closer engagement between the two. Yet the existing literature is scarce in describing the actual roles taken up by healthcare professionals in these collaborations. Addressing this gap, this article investigates the participation of healthcare professionals in medical device development in SMEs. Materials and methods: The research context is Ankara, Turkey, where most design and development activities in medical sector are geared towards export substitution, undertaken with limited resources. The analysis is based on data gathered through semi-structured interviews with 32 professionals, including design professionals, managers, physiotherapists and engineers involved in the design of around 25 medical devices. Results and conclusion: This article identifies four main roles that healthcare professionals take in medical device development: business partners, expert users, mediators, and medical professionals. These roles entail diverse responsibilities with various objects of collaboration with designers, making significant contributions to medical design.