The victim was a 47-year-old male. Macroscopically, signs of acute death and, in particular, general erosion in the mucosa of the airways and esophagus were observed. In the gastric contents, which had a pungent smell and a greenish-brown color, 5.00 g/L of propanil, 1.27 g/L of carbaryl, 0.38 g/L of ethylbenzene, and 4.0 mg/L of xylene were identified. Postmortem methemoglobinemia (45 percent) was recognized. The cause of death was considered to have been pesticide poisoning; propanil was probably most responsible for his death. The police initially considered the case to be "death with illness as the suspected cause," since no family member knew that the deceased had drunk the pesticide. Fatal cases of propanil intoxication are relatively rare, and there are few reports of such cases. Serious illness levels by propanil poisoning do not always run parallel with the dose of the pesticide. Species specificity and individual difference of metabolic rates of propanil in people are regarded as major factors, in addition to the quantity of emesis and the presence of care. Approximately 1.75 g of propanil was in the gastric contents of the deceased. Because propanil was detected in all organs inspected, as well as fatty tissue and serum, the sum of propanil in the deceased was estimated to have been about 2.42 g. The dose of the pesticide was estimated to be at least more than approximately 9.7 mL, on the basis of the concentration ratio. 1 table, 3 figures, and 19 references