This paper examines the key issues around privacy and the secondary use of data in health research from the perspective of patients and the public. It argues that there is low public awareness and understanding of the issues around medical privacy and deep public unease over the extent to which public and private bodies have access to personal information. Quoting a recent example from the field of dementia, it challenges the notion that all research is necessarily in the public interest. It argues that a socially sustainable system for the secondary use of data that preserves the gift relationship in research is dependent on there being strong systems to enforce privacy and confidentiality. Underpinning this is a need to involve patients and their representatives in the development of any new system.