Cost pressures and changes in the health care environment pose ethical challenges and hard choices for patients, physicians, policymakers, and society. In 2000 and 2001, the American College of Physicians, with the Harvard Pilgrim Health Care Ethics Program, convened a working group of stakeholders--patients, physicians, and managed care representatives, along with medical ethicists--to develop a statement of ethics for managed care. The group explored the impact of a changing health care environment on patient-physician relationships and how to best apply the principles of professionalism in this environment. The statement that emerged offers guidance on preserving the patient-clinician relationship, patient rights and responsibilities, confidentiality and privacy, resource allocation and stewardship, the obligation of health plans to foster an ethical environment for the delivery of care, and the clinician's responsibility to individual patients, the community, and the public health, among other issues.