OBJECTIVES To describe rates of inappropriate utilization, abuse, and diversion in a population of patients who were prescribed chronic opioids, as measured by urine drug testing (UDT) in the clinical setting. A secondary objective is to inform providers, payors and policy-makers about the importance of routine monitoring of patients on chronic opioids. METHODS A retrospective analysis was conducted of a database containing results from all urine drug tests conducted between January 2006 and September 2008, by Ameritox, Ltd. using their RxGuardian(sm) monitoring algorithms, for patients whose physicians ordered the test in order to screen for non-compliance. RESULTS Data from over 800,000 patient test samples obtained from over 500,000 unique patients showed that 75% of patients were deemed “noncompliant” with their prescribed pain regimen. Of patients determined to be noncompliant; 39% were found to not have the prescribed opioid present, 29% had non-prescribed opioid medications present, 27% had a drug level higher than expected, 15% had a drug level lower than expected, and 11% had illicit drugs detected in their urine. CONCLUSIONS The high observed rate of noncompliance in this patient population implies high rates of non-adherence, overuse, and diversion of prescribed opioid medications. Previous research has compared direct per-patient costs of insured opioid abusers versus non-abusers, and found significantly higher healthcare costs for opioid abusers. These higher costs have been attributed to increased utilization of services and prescription products, as well as more frequent comorbidities. Utilizing a UDT that can not only detect the presence of other non-prescribed and illicit drugs, but also is sensitive enough to determine whether the patient is adherent to their current regimen provides a powerful tool for clinicians seeking to identify and decrease noncompliance, overuse, and diversion of controlled substances in their practice.