Among patients as well as doctors it is commonly held that confidentiality has been the foundation of the therapeutic relationship since the introduction of the Hippocratic oath. Nevertheless, medical confidentiality is a controversial issue, for example in current debates on HIV/AIDS, especially with regard to the question whether sexual contacts of patients infected with HIV should be warned by doctors. Consequentialist arguments are used to justify a breach of confidence to protect other people's health, as well as to defend absolute secrecy to maintain mutual trust between patient and doctor. This article discusses the history of the debates on medical confidentiality from the nineteenth century onwards in England and Germany. Comparing the debates in these two countries shows that the issue was not confined to national borders. Furthermore, we demonstrate that the debates depended not merely on ethical arguments, but were strongly influenced by public health policies, in particular regarding venereal disease prevention, by legislation, politics and the status of the medical profession. Differences in legislation and in the social standing of the medical profession in England and Germany in particular distinguish the development of the debates in the two countries. © 2006 Institute of Materials, Minerals and Mining.