Managed care plan under which specified health services are rendered by participating physicians to an enrolled group of persons, with fixed periodic payments made in advance, by or on behalf of each person or family. If a health insurance carrier is involved, it contracts to pay in advance for the full range of health services to which the insured is entitled under the terms of the health insurance contract. Such a plan is one form of a health maintenance organization. Also called prepaid group practice model and group model health maintenance organization (HMO).