Physicians are perplexed by the ongoing erosion of their individual professional autonomy. While the economic forces underlying such change have received much attention, the evolution of new organizational forms that modify and often diminish medical autonomy is less well understood. The practice of medicine is becoming more organized and more hierarchical. We emphasize the importance of organized medical groups, including the medical staff organization, as structures for appropriate peer monitoring, and for counterbalancing the burgeoning influence of governance and administrative constraints on practice. There is an ongoing tension within organizations between management, governance, and physicians. Over time one or another of these groups achieves some measure of dominance, but good management requires a balance of power. The role of the medical staff, which is poorly represented in some health care institutions and under threat in others, is considered. In general, we find that medical work is becoming more hierarchical, and that physician "leaders" do not substitute for collegial processes.