After the general examination of blood and examinations of the leucocyte function and the pattern of their movement in 48 patients with pulmonary tuberculosis, the author studied the relationship between the results of examinations and conditions of disease; and obtained the following results: 1. The leucocyte count inceases along with aggravation of disease; and there can be observed a marked increase of lymphocytes in minimal cases; of monocytes, neutrophils and lymphocytes in moderately advanced cases; and of monocytes and neutrophils in far advanced cases. In other words, the increase in monocytes and neutrophils becomes marked as tuberculosis advances in severity. On the other hand, the percentage of lymphocytes indicates the advance of tuberculosis. Moreover, the farther advanced the disease, the more marked is the tendency of the left-shift of the nucleus in neutrophils, and also the ratio L: M decreases accordingly. Although a decrease in eosinophils can generally be observed, there is no di stinct correlation between this decrease and the condition of disease. 2. Leucocyte function: The leucocyte function in minimal cases generally is about the same as that of the normal persons, but as the disease advances to moderately advanced and to far advanced stages, it decreases along with the advance. The leucocyte function declines in proportion to the increase in erythrocyte sedimentaion rate, and those with over 25 mm erythrocyte sedimentation rate show a marked decline in the function. According to Oka's classification based on X-ray findings, the function in Type Ⅶ is markedly lower than that in Types Ⅵ, Ⅳ and Ⅴ. And according to the NTA classification as the extensiveness of lesions advances from the minimal to moderately advanced and far advanced, or according to the clinical classification as the inactive type moves to the arrest and to the active typse, the leucocyte function proportionately decreases more and more markedly. Relative to number of tuberculous bacilli, in those who are negative to bacillus culture the leucocyte function does not differ much from that of the normal, but as the culture, bacillus collection and smear specimens turn to positive, the leucocyte function gradually declines. As for the relationship with the body temperature and pulses, along with the rise in body temperature and increase in pulse-beats the leucocyte function diminishes, especially the decline is quite marked in the case with the body temperature of over 38℃ and pulses over 100. Moreover, in the case when the leucocyte count increases, the leucocyte function is enhanced up to the count of 8,000, but beyond 10,000 the function is extremely diminis hed. The greater the average number of nuclei, the greater in the acceleration of leucocyte function, and in those whose L/M ratio is 16-23, the leucocyte function is highest. Of those patients with pulmonary tuberculosis of moderately advanced stage or far advanced showing an increase in leucocyte count, a decrease in the average nucleus count, and a low L/M ratio; the ones with accelerated leucocyte function later improve, while ones with lowered leucocyte function still get worse and worse. 3. Movement pattern of leucocytes in pulmonary tuberculosis: As the disease aggravates, Types A(3), B(2), and D with low wandering velocity increase in number. In addition, even in those with the same movement pattern, as the disease aggravates, the wandering velocity decreases that much more.