Studying the influences of particular envireronment in the mountainous farm village of Hokuriku-district to serum protein fractions, and the following results were obtained. 1. In the farming seasons, in contrast to the leisure seasons for farmers, a slight decrease in total serum protein and a relative increase in α1, α2 and β-globulin were noted. 2. In the cases of malnutrition, seen during the farming seasons, a decrease in total serum protein, especially in albumin fraction, and a relative increase in α1, α2 and β-globulin were noted. 3. The changes of the serum proteins during the farming seasons were rather due to poor nutrition and fatigue than seasonable climates. 4. In the cases of pulmonary tuberculosis, increased total protein, decreased albumin and increased α1, α2 and γ-globulin were noted in the severe cases, on the other hand, in the mild or convalescent cases, a slight increase of γ-globulin was observed. 5. In the group of essential hypertension, a decrease in albumin and an increase in α1 and β-globulin were noted only in the severe cases with complications. 6. In the cases of angina pectoris with coronary insufficiency, a slight decrease in albumin and a slight increase in γ-globulin were seen, however, these changes were disappeared in the convalescent stages. In the cases of myocardial infarction, a slight decrease in total serum protein, a marked decrease in albumin and a slight increase in β and especially γ-globulin were observed. 7. In the cases of valvular heart diseases, a decrease in albumin and an increase in γ-globulin in the compensated phase, and in the decompensated phase these tendencies have become evident. 8. In the cases of stomach cancer especially of its terminal stage, a marked decrease in total serum protein, especially in albumin, and a moderate increase in γ, and a relative increase in α1, α2 and β globulin were noted. 9. In the cases of peptic ulcer, gastric and duodenal, a decrease in albumin and an increase in α1, and α2 globulin were observed. 10. In the pregnant females, no changes in serum protein fractions by 5 th month but thereafter a slight increase in α1, α2 and β-globuin and an increase in albumin were noted. These changes were evident especially in the cases of hyperemesis.