THOUGH there remains doubt as to the mechanism of production of the urticarial wheal and other reactions of allergy, most of the recent work has been based on assumption that such reactions are mediated by histamine or an H substance. Attempts at therapeutic desensitization toward histamine have utilized histamine as well as a conjugated hapten, but this approach has been time consuming and not uniformly successful. Because of its antihistamine effect Curtis and Owens1 recently called attention to betadimethylaminoethyl benzhydryl ether hydrochloride (Benadryl),2 which they used in the treatment of acute and chronic urticaria. The drug is many times more effective than theophylline ethylenediamine. in alleviating histamine shock and anaphylactic shock in the guinea pig.3 It appears to reduce bronchoconstriction, abolish vasodepressor effects and exert an antispasmodic action. Toxic effects are few and were reviewed by Curtis and Owens in their report on treatment of 18 patients