A 62-year-old male, a farmer, who had ingested prothiophos (Tokuthion), died after 21 h of intensive care. Prothiophos in the tissues of the victim was extracted and purified by Extrelut column extraction. A gas chromatograph equipped with a flame photometric detector, and a gas chromatograph-mass spectrometer were used to detect prothiophos. The concentration of prothiophos was 10.9 micrograms/g in the brain, 8.6 micrograms/g in the kidney, 418 micrograms/g in the liver, 2.96 mg/g in the gastric contents and 4.69 mg/g in the intestinal contents. The case history and the distribution of prothiophos indicated that the cause of death was acute prothiophos poisoning.