1. Seventy-two adult guinea pigs were fed tuberculous sputum daily for periods ranging from 6 weeks to 4 months. 2. Thirty-seven of these were maintained on a diet partially deficient in vitamin C; twenty-six developed ulcerative intestinal tuberculosis. 3. In the remaining thirty-five animals whose diet was supplemented by an adequate amount of vitamin C only two developed tuberculous ulcers in the intestines. 4. From these studies we conclude that the ingestion of tubercle bacilli by the guinea pig is not the sole factor in the production of intestinal tuberculosis. 5. In our opinion, an adequate supply of vitamin C usually protects the guinea pig against ulcerative intestinal tuberculosis.