1.Calves that received varying quantities of vitamin A for the first 90 days of age then were given a vitamin A-deficient ration to determine the time required to deplete their stores. The stores were considered depleted when the blood plasma vitamin A values reached 4.0 γ per 100ml.2.Two calves that were permitted to run with their dams on pasture required 4 months on the ration deficient in vitamin A to deplete their stores.3.Calves reared according to present methods of limited whole-milk feeding with hay of above average quality required a depletion time of 2 to 4 weeks.4.The feeding of hay of exceptionally good quality (high in carotene content) increased the depletion time up to 6 to 8 weeks.5.Fifty thousand I.U. of vitamin A for 50 or more days, in addition to the vitamin A received in the feed, was necessary in order to maintain stores and blood levels equal to those of calves reared with the dams on pasture. The depletion time of these calves was from 3.5 to 4 months. Feeding 25,000 or 50,000 I.U. of vitamin A under similar conditions for periods of 30 to 45 days reduced the depletion time to intervals ranging from 30 to 98 days.6.The groups that received supplemental vitamin A showed somewhat better gains, fewer cases of scours, and less mortality than the non-supplemented groups.7.The technic of determining the number of days after 90 days of age that were required for the blood plasma values to decrease to 4.0 γ per 100ml. appears to give a good estimation of the vitamin A stores.