O-Benzoylthiamine disulfide (BTDS) equivalent to 400 mg of thiamine hydrochloride or thiamine tetrahydrofurfuryldisulfide (TTFD), 200 mg and 400 mg, in the forms of two or four pills were orally administered just after a breakfast for consecutive 3 days to three healthy young men given a test diet. The feces of the former two days and the 24 hours urine after taking the pills were collected individually at the each test period of three days. Thiamine and riboflavin contents of these samples of urine and feces were determined. It was observed that average amount of thiamine excreted in the urine per person per day were 98.2 and 147.0 mg, respectively, when 400 mg of each BTDS or TTFD was given. Apparent absorption percentages of BTDS and TTFD were 61% and 57%, respectively. When large amount of BTDS or TTFD was administered, urinary excretion of riboflavin and its content in feces were lower than those of control period.