The presence of drugs of abuse in saliva of human subjects after drug administration was studied to determine the feasibility of drug testing with saliva. Healthy male subjects with a history of chemical substance abuse volunteered for the studies. Informed consent was obtained and all procedures were approved by the hospital Institutional Review Board. Following the administration of cocaine, marijuana or opiate, saliva and blood samples were collected periodically. Behavioral and physiological measures were made concurrently with collection of biofluids. Samples were analyzed by RIA and gas chromatography/mass spectrometry. Significant correlations of blood levels with saliva levels were found for cocaine and opiates. Investigations are continuing on marijuana. These studies provide the scientific basis for development of new non-invasive tests for drug abuse.