A daily dosage of 5 g ascorbate was given to 14 persons during one month. Various routine biochemical parameters were studied and the concentrations of individual bile acids in serum were determined. A significant increase in chenodeoxycholic acid concentration was found on interruption of vitamin C supplementation, whereas no other changes in bile acid concentrations were significant. One person, used to a large ascorbate intake (1 g/day), was deprived of ascorbate. On resuming the high ascorbate intake, serum bile acid concentrations showed an increasing trend. Urinary oxalate excretion and concentrations were impressively increased during vitamin C supplementation but no effects on kidney function were observed.