This paper discusses the controversy around breast implants in the United States and Europe. It focuses on the emergence of consumer and support groups for women and offers an analysis of the role they have played in recent policy developments in UK and Europe. The politics of breast implants is seen as a politics of knowledge in which scientific expertise has consistently been deployed in ways that minimize the credibility and legitimacy of women's accounts of their bodies and illness experiences. These women have been doubly disadvantaged in a policy debate that turns on scientific controversy and uncertainty. This implies a gendered dynamic to the changing relations of knowledge and expertise. The paper contributes to an understanding of the relations between regulators, manufacturers, users, and clinicians in the global medical device industry and to wider debates around the public understanding of science.