This Practice Note explains several key antitrust issues faced by health care providers and health insurers. It reviews areas of antitrust risk, including those relating to mergers, joint ventures, and contracting, and summarizes guidance from the Federal Trade Commission (FTC) and Antitrust Division of the Department of Justice (DOJ). It also provides an overview of key antitrust immunities and exemptions, including state action immunity and the amended McCarran-Ferguson exemption.