The distribution of C14 has been studied in rats following the oral administration of C14-β-carotene, which is known to be readily converted to vitamin A in the intestine. The rats were maintained in a respiration chamber and individuals removed at various time intervals up to 28 hours after dosing, and the concentration of C14 in tissues was determined. The counts per million per gram of tissue was higher in the adrenal glands and hypophysis than in the other organs examined. The pattern of C14 distribution in intestine, liver, kidneys, and blood appears consistent with current knowledge of the metabolism of vitamin A.