The increase in random urinalysis testing for employee drug use has focused attention on the effectiveness and reliability of specific kinds of urinalysis tests. The two most controversial tests, the Enzyme Multiple Immunoassay Test (EMIT) and the Radioimmunoassay Test (RIA) are discussed in detail with assessments of the scientific theories utilized in the tests and their reliability. Because the EMIT test can be administered easily by nonmedical testers, it has been selected by many companies and organizations for employee drug testing. However, the test can produce false positive results that cannot be confirmed by an alternate test, and it has caused problems of evidentiary reliability which resulted in the litigation that is discussed in detail. The reliability of the RIA test is also discussed with emphasis on military court findings. Other tests such as the Thin Layer Chromatography test (TLC) and the Gas-Liquid Chromatography test are assessed along with methods used by drug abusers to thwart positive urinalysis test results.