health maintenance organization (HMO), a type of group health care practice that provides basic and supplemental health maintenance and treatment services to voluntary enrollees who prepay a fixed periodic fee that is set without regard to the amount or kind of services received. In addition to diagnostic and treatment services, including hospitalization and surgery, an HMO often offers supplemental services, such as dental, mental, and eye care, and prescription drugs. Federal financial support for the establishment of HMOs was provided under Title XIII of the 1973 U.S. Public Health Service Act.
