The skin blood flow in the deltoid region was measured in 78 males by the Xenon 133 clearance method. A correlation was then made between age, hematocrit value, hemoglobin value and total protein determined at the time of skin blood flow measurement. From the data obtained, the following conclusions could be drawn: (1) skin blood flow significantly decreased with increasing age and with decreasing hematocrit and hemoglobin values; (2) skin blood flow showed the closest correlation with age (P < 0.001) and a weaker correlation (P < 0.01) with hematocrit and hemoglobin; (3) total protein demonstrated a significant decrease (P < 0.01) with a decrease in hematocrit and hemoglobin values giving rise to hypoproteinemia.