Urine testing is useful in identifying drug abuse when job applicants are evaluated, employee behavior indicates drug abuse, accidents indicate drug abuse, employees are enrolled in a drug rehabilitation program, and critical operating needs require periodic drug tests. If an employer uses in-house resources to collect specimens, an adversely affected employee might claim the test was rigged. This can be overcome by using third-party collectors such as biomedical laboratories and security services which provide full chain of custody documentation for the urine collections. After the collection of the urine, the first test is a screening test that identifies those specimens that appear positive. Standard practice is to screen for amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine, methaqualone, opiates, and phencyclidine. Each drug class requires a separate screening. The specimens that show positive for any of the drug classes are separated from the specimens testing negative. Confirmation tests for those specimens testing positive should be different from but at least as sensitive and specific as the screening technique. Analyses should be conducted in a sterile laboratory. It is practical to have the same laboratory perform both the screening and the confirmation tests. Although urinalysis can detect drug use, it cannot provide accurate inferences pertaining to the extent of abuse or impairment. The length of time a drug is detectable in the body depends on the drug used. Exhibits describing screening and confirmation techniques and a checklist for evaluating a laboratory.