Independent laboratories are prevalent and they are an integral part of many medical services. In this paper, we study the patient-doctor-laboratory relationship in a setting where competitive laboratories can pay the doctor kickbacks to encourage him to direct patients their way for inappropriate or unnecessary laboratory tests. Some patients are unaware that laboratories may pay doctors kickbacks and they can be hurt by the over-provision of lab tests. The aware patients use rejection of doctor's recommendations to protect themselves against overcharging. In response to the higher rejection rate when more patients become aware, the doctor charges smaller kickbacks and, consequently, induces a higher acceptance rate of lab tests. Banning kickbacks can hurt social welfare when under-provision of health services is a severe problem. A moderate level of patient awareness can be optimal for social welfare.