The authors review their experience with the implementation of a geriatric assessment unit (GAU) within the Rhode Island Group Health Association, a Health Maintenance Organization (HMO). Included is a historical background of the involvement of HMOs with care of Medicare patients, a description of the structure of an outpatient GAU, and the authors' experience to date with this population of patients. This article concludes with a discussion of the future role of GAUs and HMOs in the care of older patients.