This study was conducted to observe the effect of vitamin K on bone metabolism in postmenopausal women. Twenty-four healthy postmenopausal women recruited for this one-month, double-blind controlled study. Before and after daily administration of 1.0mg of phylloquinone the levels of serum vitamin K, osteocalcin, under-carboxylated osteocalcin, and urinary deoxy-phyidinoline were measured. The serum vitamin K concentration of Koran women as well as the average dietary intake of vitamin K was shown to be higher than the average levels of foreign women. However, no correlation between serum vitamin K concentration and vitamin K intake was found. Also, serum vitamin K concentration showed no special correlation with either bone mineral density or bone turnover markers in the study group. However, women with low serum vitamin K concentration(vitamin K-low group)had lower bone mineral density levels. After supplementation with 1.0mg/day of vitamin K, there were no changes in the levels of serum vitamin K, osteocalcin, ucOC, or u-DPD. Vitamin K supplementation did not seem to have any positive effects on bone metabolism through carboxylation. It can, however, be expected that vitamin K supplementation has a positive effect on bone metabolism in postmenopausal women with especially low serum vitamin K concentrations.