A case of lethal overdose by heroin ingestion is presented. The concentrations of drugs were measured several hours after death. Heroin, 06-monoacetylmorphine, and morphine were identified and quantitated in blood, urine, and gastrointestinal contents by gas chromatography-mass spectrometry and high-performance liquid chromatography. Concentrations of heroin, 06-monoacetylmorphine, and morphine were 109, 168, and 1140 ng/mL, respectively, in blood and 17, 12, and 425 ng/g, respectively, in gastrointestinal content. In urine, however, only morphine was detected at 3650 ng/mL.