Daily urinary and fecal thiamine excretions, test dose returns, blood thiamines and 1-hour fasting thiamine excretions of twelve women were determined on various levels of intake over a period of 8 months. Intakes of 0.14, 0.20 and 0.36 mg per 1000 Cal. were judged to be inadequate on the basis of urinary excretions and test dose returns. On an intake of 0.51 mg per 1000 Cal. the excretions increased somewhat but still remained low. That the tissues were not saturated at this level was further indicated by the facts that (1) during subsequent supplementation the excretions were higher the last 3 days than the first 3; and (2) in the final period on an intake similar to that previous to supplementation, both daily urinary excretions and test dose returns showed increases. It is suggested that the total daily thiamine intake should probably not be less than 1 mg or 20 μg per kg of body weight. Fecal thiamine excretions for different individuals were relatively constant throughout the study. Average daily urinary and fecal excretions of niacin also remained relatively constant at approximately 1.0 mg each, regardless of the levels of intake. Total excretions of pantothenic acid closely approximated the intakes at each level, by far the larger proportion being excreted in the urine.