This article surveys recent developments in federal antitrust law regarding the health professions and the delivery of medical care. In the last four years there has been a steady erosion of the affirmative defenses traditionally available to health care providers, both institutional and individual. The article surveys these developments in terms of their implications for mounting antitrust attacks against the domination of nonphysician health care providers by physicians and other sectors of the health care industry. Three specific practices are discussed in light of their susceptibility to antitrust remedy: the denial of admitting privileges, third-party reimbursement, and physician backup to nonphysician practitioners. The article concludes with some caveats and admonitions to judges presiding over any cases which arise in this area.