A random urine sample was obtained from each of 155 normal Koreans and its specific gravity (S.G.), the total osmolality (U_osm) and the concentration of chloride (U_Cl) and urea (U_urea) were determined. The U_osm, 2×U_Cl and U_urea were then plotted as a function of the S. G., and the following regression equations were obtaind: U_osm (in mOsm/kg) = 34,500 (S.G.-1,000), 2×U_Cl (in mOsm/kg) = 20,000 (S.G. 1,000), and U_urea (in mOsm/kg) = 10,000 (S.G.-1,000). The analysis of these data indicated that 58.5% of the U_osm could be accounted for by NaCl and 28.8% by urea while 41.0% of the S. G. of urine could be accounted for by NaCl and only 14.5% by urea. A comparison of these data with corresponding figures obtained from occidentals suggests that, in the Korean, the contribution of NaCl to both the U_osm and S.G. of urine is considerably higher, while that of urea is significantly lower than that in the occidental. This peculiarity of the urinary composition in Koreans is attributed to their ingestion of a low-protein, high-salt diet.