BACKGROUND Public health medicine has a potentially important role to play in influencing national health policy. This study examines the role of public health medicine in the development of the policy on coronary heart disease prevention in general practice, exemplified by the 1990 and 1993 general practitioner (GP) contracts. METHODS The methods of the study were qualitative. There were two sources of data: interviews with 33 key informants and analysis of documents relating to the policy process. RESULTS Public health medicine as an organized medical specialty had little involvement with the development of the policy. The reasons for this include a closed policy process which tended to exclude those not from a primary care background, the role of political factors, the predominance of secondary care concerns by public health medicine in the early 1990s, and differences in perspective between primary care and public health medicine. Public health medicine structures did not have systematic links with the policy process. Public health physicians working in research had more influence, but this was also limited by the absence of any systematic scientific advisory links. CONCLUSIONS To influence national policy it is necessary to have formal and informal systematic links with the policy-making machinery at all levels of the specialty.