Urinalysis results are increasingly being used by employers to detect use of prohibited substances in the workplace. As drug testing of employees becomes more common and routine, decision makers must have a clear understanding of the reliability of the methods used for urinalysis. This article assesses the accuracy and reliability of the various methods commonly used to detect drugs in urine in terms of their legal supportability. Two groups depend on laboratories' ability to legally support positive urinalysis results: the company that will use the results to commence implementation of a drug control policy, and the arbitrators, who must understand the validity of results when resolving disputes. In designing a drug testing program, a company should ensure: (1) appropriate chain-of-custody and administrative and analytical controls with documentation in the laboratory; (2) all positive results confirmed by documented methods; and (3) laboratory participation in a proficiency testing and inspection program. Tables, references