In order to study the influence of selenium (Se) on human health, the relationships between Se concentrations in whole blood and human body functions were studied in 331 healthy subjects living in Nagano Prefecture. The subjects with low concentrations of Se had lower values for hemoglobin, hematocrit, red blood corpuscles, and for the function of pulmonary ventilation, as well as lower concentrations of glucose and albumin. A lowered concentration of Se may result in anemia, even though a deficiency of iron cannot be observed. On the other hand, the subjects with high concentrations of Se had higher concentrations of uric acid, glucose and total cholesterol, higher values for diastolic blood pressure and the thickness of fat under skin, as well as a higher index of liver function. Moreover, these subjects had a good index of physical constitution and strength, and presented a large total consumption energy value. These results may show that in man, high Se concentrations in whole blood, indicate higher element concentrations in serum and better indexes of physical constitution and strength.