Professional secrecy of doctors became an issue of considerable medico-legal and political debate in the late nineteenth and early twentieth centuries in both Germany and England, although the legal preconditions for this debate were quite different in the two countries. While in Germany medical confidentiality was a legal obligation and granted in court, no such statutory recognition of doctors' professional secrecy existed in England. This paper is a comparative analysis of medical secrecy in three key areas divorce trials, venereal disease and abortion - in both countries. Based on sources from the period between c.1870 and 1939, our paper shows how doctors tried to define the scope of professional secrecy as an integral part of their professional honour in relation to important matters of public health. © Franz Steiner Verlag, Stuttgart.