This paper is concerned with changing conceptions of genetic disease. It is based on an analysis of biomedical literature and focuses on the treatment of coronary heart disease (CHD) in four published commentary papers. The aim of this analysis is to explore the ways in which CHD is constructed as genetic and the place of genetic discourses in the wider set of ideas that circulate about the disease. This analysis is then used to consider some of the claims of the geneticisation thesis (Lippman 1991, 1992). The analysis suggests that a genetic vision for understanding and managing CHD has emerged, which has many of the hallmarks of the geneticisation imagined by Lippman. However, a number of alternative and competing models of CHD are also supported within the biomedical discourse. These are related to the different disciplines with a stake in the field of CHD, and their struggles for authority. In conclusion, it is suggested that the geneticisation thesis, as a universal claim, is at odds with the diffuse and distributed nature of biomedical knowledge and practice. Rather than analysing geneticisation in a literal way, it may be more fruitful to see the thesis, itself, as a form of boundary work (Gieryn 1983).