Beware what you give them. Depending on whether you're hmo or ppo they are limited. Doctors in HMOs agree to a capitation amount which is what the insurance company agrees to pay them for specific services. They are not entitled to collect more but many will try to bill unsuspecting patients. This is where the line between billing fraud and capitation amount is crossed. Exercise your rights and don't fall victim to shady medical billing and fraud. If the doctor agreed to $20 but bills you $80 it's his tough luck. He gets $20 and is not entitled to a penny more. When the collector comes calling tell him and the doctor's office to pound sand. Threaten to report the doctor and collection/billing agency to the FTC and state insurance department. Watch how fast they back down and never try to over charge you again.