The ability to measure concentrations of cocaine in body fluids can contribute substantially to any investigation of cocaine's pharmacological effects. Design of research which involves the administration of cocaine must take into account current knowledge regarding the drug's pharmacokinetics. Cocaine's very rapid elimination from the body should be considered in attempting to understand patterns of cocaine abuse, and such phenomena as bingeing and acute tolerance. Accurate analysis of cocaine and/or its metabolites is essential to the diagnosis and evaluation of cocaine use whether for medical or forensic purposes. Appropriate selection of methods for analysis of cocaine depends upon the intended purpose of the assay, and correct interpretation of the data obtained upon knowledge of cocaine's kinetics and metabolic disposition.