1. A physician who contracts with an HMO or other insurance company to provide services to the plan’s members. 2. A physician who has agreed to accept a plan’s payments for services to subscribers (e.g., some Blue plans). Eighty percent of practicing American physicians are participating physicians. 3. Doctor or supplier who agrees to accept assignment on all Medicare claims. These physicians or suppliers may bill the patient only for the Medicare deductible and coinsurance amounts. Also called affiliated health care provider, participating provider, in-network provider, network provider.