HMO - In an HMO plan, members must choose their primary care physician from the HMO's member physicians. This Physician will oversee your heath care and must be consulted first for all medical care. If medically necessary your primary care physician will refer you to a specialist that's part of your HMO network. All medical care must be preformed by a medical provider or hospital that is in your HMO network. These programs normal provide the lowest cost. But provide very limited coverage or no coverage if medical treatment is not approved or outside the HMO network.