In the last few years there haue been considerable changes in the National Health Service. Perhaps the most significant of these has been the introduction of competition into health care, that is the split of the health service into purchasers and providers of care. Central to this development has been the introduction of general practice fundholding, whereby practices are able to purchase health care for their patients directly from competing suppliers. Those practices which have become fundholders have faced considerable challenges in developing their purchasing function. At the same time, provider units in areas where fundholding has become established face an increasingly fragmented purchasing base. Building on existing theoretical work into the nature of organizational purchasing behaviour and current knowledge of the health care market in Britain, this paper attempts to develop an understanding of the dynamics of GP fundholder purchasing behavior.