A definition of urinalysis covers the purposes of this process for drug and illegal substance detection and outlines the issues that render urinalysis a controversial subject. The issues discussed include the constitutional rights that may be infringed upon in urinalysis and the dehumanizing effects of being observed during voiding. Constitutional liberties cases and the therapeutic value of urinalysis are examined. The journey of drugs through the body is briefly traced, as is the chain of custody--i.e., the knowledge that the urine in the container when obtained belongs to the client. Laboratory terms defined and a cursory discussion of the various tests employed by laboratories in the analysis of urine--thin layer chromatography, gas-liquid chromatography, spectrophotofluorometry, immunoassays, and mass spectrometry--is given. Factors to look for in interpreting the results are identified as an extremely sensitive process requiring great caution. The presence of quinine, a substance found in medications, beverages, in pure form, and as a 'cutting' or diluting agent in the preparation of illicit drugs, is looked at as an aspect that must be considered for the protection of the client. Client subterfuges, such as flushing, switching, substituting, adding to the urine, or stalling, are dealt with as activities which must be noted by persons working with drug abusers. Mention is made of proficiency testing and quality control of urinalysis and those working in fields requiring urinalysis and those covering toxicological aspects of urinalysis.