From the factors which are considered to make an effect on circulatory or metabolic states, hemoglobin content, erythrocyte sedimentation rate, room temperature, respiratory rate and pulse rate were chosen to be discussed their relationships between the pH, P(CO(2)) and P(O(2)). Moreover, changes due to age and disease as well as diurnal and seasonal variations of blood pH, P(CO(2) and P(O(2)) were evaluated. 1) Blood pH and Peo2 showed the tendency of reduction in the order of 40~59, 10~39 and 60~79 years age group in the former and in the latter 40~59, 60~79 and 10~39 years age group. The P(O(2)) value in the afternoon decreased with ageing. However, no significance was demonstrated in any age group. 2) Diurnal changes of pH in 10~59 age group was very small. In the 60~79 age group, the afternoon value decreased than the morning one. The P(O(2)) value in the 10~59 age group increased in the afternoon contrasted to the decreasement in the 60~79 age group. The P(CO(2)) variations in all age groups were within the errors due to the measurement. 3) Rheumatiod arthritics group showed no significant diurnal variation different from non-rheumatoid arthritics group. 4) Blood pH of December-February group showed the lowest seasonal value and significant difference between March - May and September - November group. No significant seasonal variation was observed in the blood P(CO(2)) and P(O(2)). 5) The central nervous system group showed the significant lower blood pH than cardiovascular disease and rheumatoid arthritis group. The P(CO(2)) values of rheumatoid arthritis group were lower significantly than cardiovascular disease, central nervous system, and musculo- keletal system patient groups. None of diseases showed significant P02 difference each other. 6) Significant relationship was demonstrated between erythrocyte sedimentation rate and P(O(2)) value only in cardiovascular disease patient group. 7) There were the significant relationships between room temperature and P(O(2)) in rheumatoid arthritis and metabolic disease groups. 8) Significant relationships were shown between respiratory rate and pH in rheumatoid arthritis and cardiovascular disease groups. 9) There was significant relationship between pulse rate and pH only in rheumatoid arthritis groups. 10) The combination of the blood pH, P(CO(2)) and P(O(2)), values was shown to reflect the circuratory or metabolic states of the tissues or organs and to remain stable on the experimental day.