AFTER GIVING 10 MG OF MORPHINE HYDROCHLORIDE OR METHAMPHETAMINE HYDROCHLORIDE ORALLY TO VOLUNTEERS, URINE AND SWEAT WERE COLLECTED IN INTERVALS. THE SWEAT WAS COLLECTED BY RUBBING THE SKIN WITH COTTON OR A TOWEL AT 50 DEGREES CENTIGRADE. FOR THE DETECTION OF MORPHINE, THE SWEAT EXTRACT WAS FREEZE-DRIED WITH THE AID OF ROTARY EVAPORATION. HOMOGENEOUS ENZYME IMMUNOASSAY WAS USED FOR THE TESTS OF THE URINE AND SWEAT. THE SWEAT EXAMINATION PRODUCED THE SAME ACCURACY AND CUT-OFF LEVEL AS THE URINE TEST. THE PRESENCE OF MORPHINE IN THE SWEAT COULD ALSO BE CONFIRMED BY GASCHROMATOGRAPHIC AND GASCHROMATOGRAPHY-MASS SPECTROMETRIC ANALYSIS ACCORDING TO THE METHOD OF WILKINSON ET AL. THE CONDENSION OF THE SWEAT EXTRACT BY FREEZE-DRYING OR EVAPORATION COULD NOT BE ACHIEVED FOR THE METHAMPHETAMINE BECAUSE OF ITS HIGH VOLATILITY. THE DRUG WAS EXTRACTED ACCORDING TO THE METHOD OF JAIN. THE EXCRETION OF THE DRUG INTO THE SWEAT REACHED ABOUT THE SAME AMOUNT AS WAS ELIMINATED THROUGH THE URINE. GASCHROMATOGRAPHY WAS USED TO DETECT THE METHAMPHETAMINE. THE TESTING OF SWEAT TO DETERMINE DRUG USE IS PRACTICAL WHERE THE SUBJECT REFUSES TO DELIVER OTHER SPECIMENS. MANY ALKALOIDS AND BARBITURATES ARE EXCRETED IN THE SWEAT ALSO, AND CAN BE DETECTED QUANTITATIVELY BY THE SAME PRINCIPLES USED IN THE EXPERIMENT. GRAPHIC AND TABULAR DATA AND REFERENCES ARE PROVIDED. (RCB)