What is an HMO?

HMO stands for Health Maintenance Organization. Health Maintenance Organizations (HMOs) are only one of many types of managed care arrangements. Individuals who join an HMO are considered members. Typically HMOs provide members with comprehensive health care including preventative health services. When someone joins an HMO, they select a primary care physician from the list provided by the HMO. That primary care physician coordinates all of that member's medical care. If care by a specialist is needed, the primary care physician will refer the member to a specialist who is usually also in the HMO network. Members who go outside of the network to receive care (unless given prior approval) will probably pay all or most of the cost of that care out of their own pockets.

Gail Carlson, MPH Ph.D., Continuing Medical Education, School of Medicine, 
University of Missouri-Columbia