Thirty-one patients with palmonary tuberculosis were found in 157 patients with diabetes who were diagnosed at the National Seoul Hospital from Jan.'78 to Dec.'81. 1) Male(21 cases) and female (10 cases) ratio of the patients was 2.1:1. The highest incidence was seen in the 40 th decade, and the next in fifth decade. .2) The incidence of pulmonary, tuberculosis in patents with diabetes mellitus was higher than those without diabetes. 3) Far advanced pulmonary tuberculosis was most common on chest roentgenograms. Caviatation occurred in 76% of all cases. 4) It seems that the severity of diabetes mellitus do not effect the prognostic course of pulmonary tuberculosis, in 3 month-follow-up study 5) It is most likely that diabetes mellitus may be predispossing or aggravatinirg factor of pulmonary tubeculosis, but does not affeet the course of puImonary tuberculosis.