Citizen participation in deliberation activities within public health systems is increasingly seen as essential in achieving more patient-centred, equitable and democratic care. However, recent studies show that patients' lived, affective experience of illness and care remains poorly understood within deliberative fora. In response, this article argues that emotion is central in mediating deliberation, and in conditioning deliberative outcomes. To understand how this occurs, we use a sociologically informed notion of ‘biographical affect’ to address links between emotion and social and political action. Benefits of this approach for healthcare deliberation are illustrated through an in-depth case study of a major citizen participation forum in the UK National Health Service. Our conclusions call for alternative orientations to participation that involve committed engagement with participants' affective experiences.