A review of information on the production, uses, exposure and health effects of 4,4'-diaminodiphenylmethane (101779) (DDM) is presented. Most DDM has been used in the production of isocyanates and polyisocyanates which are used in the manufacture of polyurethane foams. DDM has been used as: an epoxy hardening agent; a raw material in the production of polyurethane elastomers, Qiana nylon and poly(amide-imide) resins; a neoprene curative; and an antifrosting agent in footwear. Approximately 2,500 workers have been exposed to DDM. Instances of toxic hepatitis in humans exposed to DDM through accidental contamination of bread or through occupational exposure were described. There were six cases of hepatitis among about 300 men using epoxy resins at a nuclear power plant construction site. Over a 6 year period, 13 workers who used DDM in the production of hard plastic insulating material developed hepatitis. A single case of acute hepatitis, with central nervous system and pulmonary symptoms, was reported by a person who was exposed to a surfacing agent containing DDM. Three experimental studies on the carcinogenic effects of DDM in rats were described. Based on the 1 to 2 percent incidence of liver disease noted in a study of nuclear power plant construction workers exposed to DDM, and the possibility that not all workers are susceptible to liver injury from DDM exposure, approximately 25 to 50 cases of DDM associated toxic hepatitis would be expected per year.