The purpose of this research was to determine the relationship of the dietary nutrients to blood pressure among preschool children in Seoul and to concurrently study the effect of seasonal variance on the aforementioned relationship. The subjects of the study consisted of 203 preschool children aged four to six years. Anthropometric measurements of height, weight, pulse rate and blood pressure, urinary excretion of five cations(Na, K, Ca, P, Mg), creatinine and urea nitrogen and dietary questionaires concerning sodium, potassium calcium and phosphorus were taken during the two periods of summer(Aug. 1986)and winter(Feb, 1987). The results obtained are summarized as follows: 1) The daily urinary excretion of five cations, creatinine and urea nitrogen is summer and winter was as follows; The sodium content was 57.8 mEq in the summer and 59.4 mEq in the winter ; potassium 20.4 mEq and 23.0 mEq, respectively ; calcium, 5.5 mEq and 3.6 mEq, respectively ; and phosphorus, 27.4 mEq and 19.9 mEq, respectively. Only calcium and phosphours excretions in the urine showed significant differences per season(p<0.05). 2) The average dietary intake per day of sodium was 2349mg in the summer and 2155mg in the winter ; potassium consumption was 1425mg in the summer and 1448mg in the winter ; intake of calcium was 472mg in the summer and 500mg in the winter ; and phosphours consumption was 642mg in the summer and 634mg in hte winter. The sodium-to-potassium consumption ratio 1.6 and 1.5, respectively, in the summer and in the winter and the calcium-to-phosphorus ration was 0.7 in the summer and 0.8 in the winter. The dietary calcium intake showed significant differences between the seasons. 3) The principal source of sodium consumption among preschool children was from seasoning-including talbe salt, soy sauce and instant sauce-which accounted for higher then 45% of the sodium intake in both seasons. The main source of potassium was frutis and vegetables which accounted for 29.6% of the potassium intake in the summer and 25.7% in the winter. Milk and milk products were the primary dource of calcium(higher then 40% in both seasons) 4) In the summer, urinary phosphours levels were weakly reated to systolic blood pressures. (0.05<p<0.1) Urinary magnesium levels were positively related to systolic blood pressures(p<0.05) 5) Systolic blood pressures were significantly correlated with the intake of only one nutrient, calcium, in the summer(p<0.05), and calcium-to-phosphorus ratio negatively correlated with systolic and diastolic blood pressures(p<0.05<0.1). In the winter, the only association between systolic blood pressures and dietary sonsitituents was exhibited in the sodium intake(p<0.05). while sodium-to-prtassium ratio showed stronger postive correlation with systolic blood pressuers(p<0.01).