A man was found dead in a tank where gaseous dimethyl sulfide (DMS) was present. The concentrations of DMS in the blood and tissue samples were measured by gas chromatography. Mice were experimentally exposed to various concentrations (5%-55%) of gaseous DMS in a confined space and the course of death and DMS distribution in the bodies were observed to obtain diagnostic criteria for DMS poisoning. As a result it was considered that the cause of death of the victim was consistent with a combination of DMS poisoning and asphyxia due to a hypoxic atmosphere.