With Shetlar's method the author conducted determination of polysaccharide in serum of 68 patients with pulmonary tuberculosis. As for the control ten normal persons were selected; and the pulmonary tuberculous patients were consisted of 23 of minimal cases; 20 of moderately advanced cases; and 25 of far advanced cases. In addition, by studying the relationship between the blood sedimentatation rate and the results of liver function, the author arrived at the following conclusions: 1) Serum polysaccharide in pulmonary tuberculosis has been greater than that in normal persons. 2) In the patients with pulmonary tubercnlosis the amount of serum polysaccharide has increased in accordance with the widening of the tuberculous focus and the enlargement of the cavity, which seems to be a useful criterion for the determination of the stage of pulmonary tuberculosis. 3) The serum total protein in the patients is greater than that in the normal, and there is a parallel relationship between the serum total protein and serum polysaccharide. 4) In the pulmonary tuberculosis with complication of empyema the ratio of non-glucosamine polysaccharide to serum total protein (N.G.P./S.T.P.) is markedly increased, showing over a. 2.0% increase in the entire group. 5) In the patients with pulmonary tuberculosis a certain degree of parallel rerationship can be recognized between the blood sedimentation rate and N.G.P./S.T.P. 6) No intimate relationship can be recognized between the liver function and serum polysaccharide in the pulmonary tuberculosis.