MALATHION IS the commonly-used name for the pesticide (0, 0-dimethyl dithiophosphate of diethyl mercaptosuccinate). Although a member of the cholinesterase-inhibiting group of pesticides, it is far less active as a cholinesterase-inhibitor than any other member of this class presently known. A number of reports have emphasized the relative safety of this compound, even when applied directly to the human skin. Because of its effectiveness against pests and its apparent low degree of toxicity to man, the product has achieved widespread distribution and use. Recently, we have observed a child with transient encephalopathy following exposure to this insecticide in the form of a commercially available aerosol. Report of a Case On Dec. 6, 1960, the parents of a 3-year-old boy discovered him in the basement of their home holding an aerosol bomb containing malathion in a 0.5 per cent concentration. Approximately 4 oz. of the mixture was missing. The spray was