An analytical method for the determination of sulfide in human and rat brain is described. It utilizes a continuous flow gas dialysis pretreatment and quantitation by ion chromatography with electrochemical detection. Rat brain sulfide levels were reliably measured after fatal intoxication by intraperitoneal injection of NaHS. By expeditious analysis of samples it was possible to demonstrate the presence of endogenous levels of sulfide in both rat and human brain as well as to measure elevated brain levels of sulfide after intoxication. In postmortem rat brain tissue, elevated sulfide levels could still be reliably demonstrated 96 h after death if the bodies had been refrigerated at 4 degrees C. Two case studies of human hydrogen sulfide inhalation fatalities are presented. The described method was able to measure significantly elevated sulfide levels in both cases.