The total nitrogen, protein nitrogen, nonprotein nitrogen, free amino acid nitrogen, and nitrate content of cabbage, carrot, Chinese cabbage, cucumber, eggplant, green gram sprouts, Japanese radish, lettuce, onion, spinach, tomato, and welsh onion were determined. The distribution of protein nitrogen and nonprotein nitrogen in the 12 kinds of vegetables averaged 45.6 and 54.4%, respectively, of the total nitrogen present. Of the total nitrogen, 29.9% was the free amino acid nitrogen. Concentrations of nitrate were above 2000 ppm in cabbage, Chinese cabbage, Japanese radish, lettuce, and spinach. Since the current method for determination of the protein content in the Standard Tables ofFood Composition in Japan converts nitrate nitrogen into ammonium nitrogen, we believe that the protein content of Japanese vegetables has been overestimated. A portion of the nitrogen intake currently assessed as protein nitrogen is likely nitrate nitrogen. Public concern has arisen over the possible negative effects of excess dietary nitrate (I. A. Wolff and A. E. Wasserman, Science 177, 15-19). Some attention has been paid to the influence of genetic variation, fertilization, and other agronomic factors on the nitrate content of vegetables. This work suggests that the factors for calculating the protein plus free amino acid content from the total nitrogen content (except nitrate nitrogen) for vegetables should be 4.7 instead of 6.25. 0 1987 Academic h, IIX.