Patients entering a hospital with a variety of complaints are often found to have low levels of ascorbic acid in the plasma if determinations of this factor are made. In some cases in which diagnosis or treatment may be facilitated by the restoration of vitamin C in the tissues, rapid saturation is desired. To accomplish this efficiently, it is necessary to determine the maximum dose that will not cause increased urinary excretion of ascorbic acid. Obviously the total dose required for saturation depends on the state of deficiency of the body tissues, and one can judge that amount only by some indirect index of the status of the tissues. It has been argued that the plasma level of ascorbic acid is a poor index, and attempts have been made to find more reliable criteria for the state of vitamin C nutrition. Studies of excretion, although extensive, have not established a