215 ILCS 5/370b
Notwithstanding any provision of any individual or group policy of accident and health insurance, or any provision of a policy, contract, plan or agreement for hospital or medical service or indemnity, wherever such policy, contract, plan or agreement provides for reimbursement for any service provided by persons licensed under the Medical Practice Act of 1987 or the Podiatric Medical Practice Act of 1987, the person entitled to benefits or person performing services under such policy, contract, plan or agreement is entitled to reimbursement on an equal basis for such service, when the service is performed by a person licensed under the Medical Practice Act of 1987 or the Podiatric Medical Practice Act of 1987. The provisions of this Section do not apply to any policy, contract, plan or agreement in effect prior to September 19, 1969 or to preferred provider arrangements or benefit agreements.
215 ILCS 5/370b