To assess Vitamin K (VK) status by food questionnaire, healthy young males (32) and females (9) were given a food list of 50 VK rich foods (identified in the 4th edition standard tables of food composition in Japan). After checking the food names and approximate amount eaten for 7 days, early morning blood and urine samples were collected. Prothrombin and hepaplastin was tested and plasma protein induced by VK absence factor II (PIVKA-II), osteocalcin, and calcium, phosphorous and magnesium in plasma and urine were determined. Participants who have a habit of eating natto, a traditional Japanese food very rich in Vitamin K, VK were excluded, and lowest and highest VK consumers were compared (males; lowest 7 vs. highest 7, females; 3 vs. 3). Plasma PIVKA-II levels, and urinary calcium and magnesium excretion of the lowest was significantly higher, but urinary phosphorus was lower, than that of the highest in females. In the natto eaters, daily mean VK intakes and hepaplastin test results of natto eaters were significantly higher, but urinary calcium excretions were lower than that of non natto eaters in males. These results suggest that Daily VK intake estimated from a questionnaire, is well related to real VK status, and also that natto is a good dietary source of vitamin K.