Five subjects received 3 single intravenous doses of heroin, 2.5, 5, andd 10 mg per 70 kg and 1 oral dose of dextromethorphan, 60 mg per 70 kg; another 4 subjects received morphine, 30 mg, subcutaneously, 4 times per day for 3 months. Saliva and plasma samples were collected at intervals for 48 hours following each single drug dose and hourly for 6 hours between chronic doses. Plasma samples were analyzed for opiate by RIA, and saliva samples by RIA, a modified FRAT, and the EMIT. The low dose of heroin was not consistently detectable at any sampling time in either the plasma or the saliva. The medium and high doses were detectable with high probability for 2 to 4 hours in plasma and 1 to 2 hours in saliva. Dextromethorphan was not detectable in plasma hut was detected with high probability in saliva for 30 minutes by EMIT and 2 hours by FRAT. During chronic administration there were high probabilities of detection of morphine in plasma for at least 6 hours and in saliva for 3 to 4 hours after the last morphine dose. While these fluids do not appear to be as useful as urine in routine screening for herOin, they may be useful in the detection of high‐dose chronic abuse.