When allied teams entered Germany after the war, they found the Germans using, for control of aphids, an insecticide which had been developed as a substitute for nicotine. The active ingredient of this compound was tetraethylpyrophosphate (TEPP), a powerful cholinesterase inhibitor. This insecticide recently has been made available in this country, one of the commercial preparations being vapotone-XX.® The label of the manufacturer1lists the ingredients as tetraethylpyrophosphate 20 per cent, related organic phosphates 30 per cent and inert ingredients 50 per cent. Recently a case of poisoning due to agricultural use of this compound was encountered. REPORT OF CASE A Negro aged 17 was admitted on the evening of June 14, 1949, retching, salivating profusely and in a semistupor. It was difficult to obtain an adequate history, and all that could be learned was that he had been spraying melons with vapotone.® The next day a more complete