In 1940 Culbertson1 reported the successful action of quinacrine hydrochloride (atabrine® dihydrochloride) in the elimination of the tapeworm Hymenolepis fraterna from mice. He described the ready penetration of the wall of the small intestine by the drug, particularly in areas where the parasite is found. Later, in 1946, Saccomanno2 reported the use of quinacrine in infestations with Taenia saginata. We have used quinacrine with success in the treatment of 11 patients with teniasis. Because reports of the effectiveness of quinacrine in such infestations are chiefly in the Latin American literature,3 we are recording our experiences with this drug. The general plan of treatment that we have followed is adapted from that described by Saccomanno and Rivero. On the day preceding treatment the patient received a milk diet with the expectation that roughage would be eliminated from the gastrointestinal tract, leaving the worm adequately exposed to the action