For the purpose to know changes in blood contents, seasonal changes and changes by age in blood contents of peasants and fishermen were studied, while comparing the results reported by other authors. During our surveys we gave them advice according to the results of the examination. 1) As a result it has been found that relation exists in males between the blood contents and age, but it was not clear in case of females. 2) Increase in the blood contents can be observed in peasants and fishermen irrespective of seasonal changes. 3) Decrease in the blood contents was recognized in summer. 4) Anemia in the farmers engaged in vinyl green house culture seems to be intimately associated with the serum iron concentration. The seasonal changes in the serum iron concentration occur, that is to say, the serum iron concentration in peasants and fishermen decreases in summer, but increases again in autumn, however, it does not increase in farmers engaged in vinyl green house culture. 5) It has been also demonstrated that a correlation exists between the specific gravity of the whole blood. 6) Changes in the blood contents of males seem to be less than those of females. 7) A correlation of the blood contents is found existing between man and wife.