The response in terms of urinary excretion to a large dose of vitamin C administered orally has been widely used during the past few years as an indication of vitamin C saturation of the body.1 The amounts and the mediums (i. e., orange juice, tomato juice and crystalline vitamin C) have varied, but the method of administration has been by mouth. The possibility of error in such a test is now known to be great, owing to the variation in absorption and utilization of vitamin C from the gastro-intestinal tract as a result of varying degrees of acidity (anacidity), inflammation, the introduction of laxatives and other less understood factors. We have found this to be the case frequently.2The same objection holds for tests which involve studies of the blood level after the oral administration of this substance. Moreover, the level of excretion at which continued daily doses