The relevant published toxicological and pharmacokinetic data on the effects of industrial monosulfhydryl hydrocarbon (MSHC) compounds in humans and animals have been reviewed. These compounds are of occupational and environmental exposure concern to humans because they are manufactured in significant quantities, widely used, and insufficiently studied for long-term exposure effects and epidemiology. Both human and animal exposure studies indicate that the inhalation of low molecular weight (C1-C8) compounds at high concentrations may produce severe central nervous system depression and respiratory paralysis. Short-term inhalation at microgram per liter concentrations does not cause any significant toxicity in humans, but the odors do cause environmental concern. Some delayed toxicity and mortality are seen after subchronic exposure in animals. Respiratory organs are significantly damaged by the inhalation of MSHC compounds, whereas some organ pathology is observed in the spleen, liver, and kidneys after oral and intraperitoneal administration. Dermal toxicity is observed for several high molecular weight compounds (> C8). Of all the compounds tested, monosulfhydrylbenzene is most injurious to the eyes, whereas other compounds cause moderate irritation. Major detoxication products of MSHC compounds are carbon dioxide and urinary inorganic sulfate. Methylation and oxidation are the major pathways for detoxication, with the lungs and kidneys being major organ routes of excretion.