Fatal hydrogen sulfide poisoning. 
Two cases of fatal hydrogen sulfide poisoning are described which occurred during cleaning of a tank that had transported polysulfides.  The most characteristic findings of the autopsy were: a blackish-green pigmentation at macroscopic examination; pulmonary edema, steatosis, intrahepatic cholestasis and renal tubular necrosis at microscopic examination.  The blood concentration of sulfide ions exceeded 3.5 mg/l. These cases are compared to others described in the literature.  The preventive measures that should be adopted to avoid this type of poisoning are stressed.