Protein malnutrition of children is one of the most serious nutritional deficiencies in developing country. Urea nitrogen excretion in ureotelic animals is the function most sensitive to dietary protein. The 24 hours excretion of creatinine in the urine of a given subject is remarkably constant from day to day. The creatinine excretion of different individuals of the same age and sex is also quite constant. Low ratios of urinary urea to creatinine are found children low protein intake. The foregiving world-wide investigations indicate that the urea nitrogen/creatinine ratios seems to be a good biochemical indicator to distinguish among group with different levels of protein intake. The purpose of this study is to evluate an indicator of protein intake on the elementary school children ranged from 6 to 8 years of age living in rural and urban areas. Each child measured for height and weight of body. weight measured by means of a plate from scale and height by a vertical measuring rod. Biochemical test were taken from a finger-tip and urine. Hemoglobin level in the blood was measured by cyanomethemoglobin method. From the urine samples, urea nitrogen and urea creatinie were determined by Folin-Wu method and: calculate the ratio. The following result were obtained: 1) Mean of the body weight and height in urban children(Seoul) was higher and heavier than rural children(Kyunggi, Kangwon). And 12% of boys, 18% of girls in Kyunggi and 25% of boys, 22% of girls in Kangwon area weight less than 80% of Korean Physical Standard weight level. 2) The mean hemoglobin values of boys and girls in Seoul are children were 13. 3g/100ml, 13.1g/100ml and the mean of hemoglobin values in Kyunggi 12.9g/100ml of boys, 12.4g/100ml of girls, and 12.4g/100ml of boys, 12.9g/100ml of girls in Kangwon children. It is found that 22% to 24% children inrural area (Kyunggi, Kangwon) had hemoglobin level less than 12g/100ml which means anemia. 3) The mean of hematocrit level of Seoul, boys and girls children were 33.5%, 34.1% and 33.4%, 33.1%, in Kyunggi area and 33.1%, 32.9% in Kangwon area. 4) Urea nitrogen/creatinine ratios in Seoul children were 9. 0, 10. 0 of boys and girls, the ratio were 8.2, 8.0 in Kyunggi boys and girls children, and 7.5 and 7.4 in Kangwon boys, girls children. Low-income rural and upper-income urban background large differences between two groups in the urea nitrogen/creatinine ratio(Seoul: Kangwon in male, female children. p<0.05, p<0.001). The urea nitrogen/creatinine ratio definetly seems to be a good indicator of the quantity of the protein intake. However, whether or not it is an indicator of the quality of the ingested protein ramains to be seen.