Poisoning by hydrogen sulfide has been recognized as an occupational hazard for at least two centuries. The development of alternative sources of energy in North America may increase the incidence of this medical emergency in the future. Until recently, no specific antidote to sulfide was recognized. We have compared sulfide poisoning to cyanide poisoning and documented recent findings that indicate many similarities between the two. The therapeutic induction of methemoglobinemia, as by the intravenous administration of sodium nitrite, has both protective and antidotal effects against sulfide as well as against cyanide in laboratory animals. This procedure has been used successfully in at least one severe human case of sulfide poisoning. Industries at risk should be prepared to initiate this form of therapy in addition to the usual measures for cardiopulmonary resuscitation. No evidence exists to suggest that sulfide poisoning results in an impairment of the oxygen transport capability of blood. On the other hand, some victims of hydrogen sulfide poisoning exhibit frank cyanosis, suggesting that the respiratory tract obstruction is more common in this condition than is generally recognized. Suction of the upper tract and the administration of oxygen may be important ancillary procedures to the administration of sodium nitrite.