PATHOLOGICAL LESIONS IN MICE AND RATS CAUSED BY DYESTUFFS RHODAMINE B AND METANIL YELLOW. Rhodamine B and Metanil Yellow are 2 non-edible dyestuffs which are widely used for coloring snacks and drinks in Jakarta. These substances are reportedly toxic for human beings, however no data on acute or chronic intoxications are available so far. Groups of mice and rats were fed with either Rhodamine B or Metanil Yellow. The doses of these dyestuffs varied from 0.5 mg to 1350 mg per kilogram body weight. These animals were dcvided into 3 different experimental groups, respectively acute, subacute and chronic toxicity tests. Clinical signs included discoloration of the skin and its intensity depended upon the concentration of the dyestuffs used. The body weight gain of the test animals were consistently lower than those of the controls. Some animals became agressive and cannibalism occurred. Pathological lesions consisted of unthriftiness, focal liver inflammation, hydronephrosis, hepatoma and lymphoma. Considering the results of the experiments, it is justified to warn that the wide use of Rhodamine B and Metanil Yellow for food coloring might be hazardous for human health.