Statistical investigations of various milk-solids calculating formulas had been performed with 228 samples of Holstein's milk during June in 1956 to Dec. in 1958. The specific gravities and fat contents of them lowered slightly in summar, but their SNF contents decreased remarkedly in the season. Then, significant difference was also observed in summar between the calculated and determined milk-solids contents. This fact was resulted from the lowering of SNF content, so the use of correcting factor was neccessary to obtained better results. Similar results were observed in October's samples. There were no significant differences in the chemical components of milks colected from the older, pre-war, experienced farmers and unaccustomed new ones.