The effect of vitamin C on the intestinal absorption of vitamin A was observed in the rat. The various protein content diets (rice, 10% casein added in rice, 10%, and 30% casein) were fed. Vitamin A (2,000-40, 000 IU) and vitamin C (10 ㎎) at each day were administered for 3-7 days by the tube-feeding and the intraperitoneal injection, respectively. Vitamin A content in serum and liver was determined by the method of Oser et al. (1943). The following results were obtained: 1) Vitamin A content in the serum was increased by vitamin C in the all in vivo experiments, and 30% casein diet enhanced vitamin C effect on the increasing content as compared with 10% casein diet. 2) Vitamin A content in the liver was increased by the vitamin C in 10% and 30% casein diets. 3) Vitamin C did not significantly change the net vitamin A content in serum and liver in the isolated perfused system. These results may indicate that vitamin C may give effect on the enhancement of the intestinal absorption of vitamin A, but not on the circulatory transport into the liver.