The clincial diagnosis of cocaine abuse is more difficult than previously recognized. The laboratory can play an important role in helping identify cocaine abusers and also in monitoring the progress of their recovery. An overview of the role of the laboratory is presented with the goal of optimizing the clinician's ability to apply available technology in an efficient manner. Various chromatographic and competitive binding techniques for the detection of cocaine and its metabolites in biological fluids are discussed and limits of each technique is identified. The cases of false negative and false positive results are explored and an approach to maximize benefits and economics of testing is described.