Abstract 1. 1. Twelve patients with therapeutic malaria were studied before, during, and after the malaria with regard to liver function. Four laboratory tests, the cephalin-cholesterol flocculation, the quantitative serum bilirubin, the quantitative Ehrlich reaction, and the bromsulfalein test, were used. 2. 2. Alternate patients, six of the twelve, were given 8.1 Gm. of methionine orally per day in addition to a general hospital diet. The other six served as controls and received the same diet without extra methionine. 3. 3. All twelve of the patients studied exhibited some evidence of disturbed hepatic function as measured by the four tests. 4. 4. In ten of the twelve patients, there were functional abnormalities from one to three days after the termination of the malaria. 5. 5. The daily addition of methionine to the diet failed to provide any evidence of protection of liver function.