THERE is only one report in the literature regarding the blood volume in pulmonary tuberculosis. Allbritten and co-workers,1 using the Evans blue dye method, found that in 10 patients there was an average reduction in blood volume of approximately 15 per cent. These workers did not discuss the total red cell volume or plasma volume in their patients. Muller2 in his monograph on the blood in tuberculosis discusses the red cell count, particularly from the standpoint of anemia. In general, in Muller's frequency diagrams, the means and range for the red blood cell count, hemoglobin concentration and hematocrit in patients with pulmonary tuberculosis, both male and female, are approximately the same as normal values, with the exception that the range is somewhat greater in patients with pulmonary tuberculosis. Also mentioned was the possibility that some patients may have secondary polycythemia, although no data regarding this were given.