The purpose of this study was to define a one portion size of food frequently consumed by Korean children aged 6-11 for convenient use in food selection, diet planning, nutritional evaluation, and nutrition education. We analyzed using the original data on 889 persons (9.96%) aged 6-11 years among 8,930 persons to whom NHANES 2005 and selected food items consumed by the intake frequency of 10 or higher among the 500 most frequently consumed food items. A total of 172 varieties of food items of regular use were selected. Also the portion size of food items was set on the basis of the median (50 percentile) of the portion size for a single intake by a single person was analyzed. The portion size of cereals was 5 g for prosomillet to 120 g for hamburger. As for vegetables, it posted 1 g for red pepper to 50 g for nabakkimchi. The portion size of meats and products was 15 g for luncheon meat to 120 g for beef feet soup. In comparison of children's portion size with adults', the children's portion sizes of every food groups, with the exception of meats and eggs, were lower than those of adults. The portion size of the regular food items of children in this study will be conveniently and effectively used by children, children's diet planners and researchers in selecting food items for a nutritionally balanced diet and in assessing the children's diet intake.