Recent studies have shown that the urinary excretion levels of water-soluble vitamins can be used as biomarkers for the nutritional status of these vitamins. To determine changes in the urinary excretion levels of water-soluble vitamins during pregnant and lactating stages, we surveyed and compared levels of nine water-soluble vitamins in control (non-pregnant and non-lactating women), pregnant and lactating women. Control women (n=37), women in the 2nd (16-27 wk, n=24) and 3rd trimester of pregnancy (over 28 wk, n=32), and early- (0-5 mo, n=54) and late-stage lactating (6-11 mo, n=49) women took part in the survey. The mean age of subjects was ~30 y, and mean height was ~160 cm. A single 24-h urine sample was collected 1 d after the completion of a validated, self-administered comprehensive diet history questionnaire to measure water-soluble vitamins or metabolites. The average intake of each water-soluble vitamin was ≈ the estimated average requirement value and adequate intake for the Japanese Dietary Reference Intakes in all life stages, except for vitamin B₆ and folate intakes during pregnancy. No change was observed in the urinary excretion levels of vitamin B₂, vitamin B₆, vitamin B₁₂, biotin or vitamin C among stages. Urine nicotinamide and folate levels were higher in pregnant women than in control women. Urine excretion level of vitamin B₁ decreased during lactation and that of pantothenic acid decreased during pregnancy and lactation. These results provide valuable information for setting the Dietary Reference Intakes of water-soluble vitamins for pregnant and lactating women.