Aqueous dispersions of β-carotene were injected intravenously to the rats fed on the basal diet containing no vitamin A, carotene and fat, or on the basal diet added with vitamin A or fat or both of them. Corn oil was used as the fat source, therefore it must be considered that it acted not only as a fat, but also as tocopherol contained. The fecal excretion of carotene increased by the addition of vitamin A or corn oil to the basal diet, especially by the former. The tendency of decrease of carotene excretion became considerable with progress of vitamin A deficiency. It was presumed that vitamin A deficiency may impair the conversion of carotene to vitamin A. The rats fed the diet with corn oil utilized carotene more effectively than the rats in the fat deficient diet.