Medical literature reveals extensive work on cholesterol and plasma protein content of the blood in health and in various diseases, but only a limited number of the reports contain data on pulmonary tuberculosis. Since the onset and the course of development of tuberculosis are comparatively slow, the changes in the blood are likewise slow, in striking contrast to the rapid changes found in pneumonia. As a result of this gradual change, various stages of tuberculosis present chemical pictures as opposite as those found in different diseases. Therefore, to formulate definite conclusions regarding chemical changes in the blood, repeated examinations supplemented with clinical observation should be made on subjects representing all stages of tuberculosis. The purpose of this work is to ascertain a possible relationship of the plasma proteins, cholesterol and corpuscle volume to the different stages of tuberculosis. Single determinations were made on seventyone patients, and repeated determinations on thirty-eight.