(1) A severe granulocytopenia or anemia, or both, have been produced in rats fed sulfathiazole, sulfadiazine or sulfanilamide at a 1 per cent. level in purified diets. (2) Treatment with certain liver fractions orally has succeeded in correcting the granulocytopenia in four days and the anemia in about 10 days in spite of continued ingestion by these animals of the sulfonamide-containing diet.