Random drug testing is used as a preventive and detection tool for drug or alcohol use, and medication compliance in the monitoring of regulatory and treatment compliance monitoring. Urine screening is generally viewed as the preferred method for assessing substance use and may be supplemented with hair, blood or nail testing to assess for drug use over long periods. A positive drug test does not provide information about the levels of impairment but only that a drug or substance was used within the detection period and requires immediate attention. Selection of competent laboratories and Medical Review Officer support is essential to ensure accurate drug testing and evaluation.