From April to August 1967, nine cases of a clinically distinct illness characterized by fever and profuse sweating occurred in a small nursery for newborns in St. Louis, Missouri. Two of the cases were fatal. Only after the ninth case developed was it discovered that an antimildew agent, containing a high concentration of sodium pentachlorophenate (the sodium salt of pentachlorophenol), was being used in the hospital laundry. All of the clinical, epidemiological, and biochemical evidence indicated that this outbreak resulted from pentachlorophenol poisoning. The only identified mode of exposure was skin absorption of sodium pentachlorophenate residues on diapers and other fabrics, resulting from the misuse of the antimildew agent in the final laundry rinse.