We studied the effect of abdominal surgery on the development of pulmonary tuberculosis using 74 patients treated for active pulmonary tuberculosis for the first time. Group I consisted of patients (53) without a history of abdominal surgery, and Group II consisted of patients (21) with a history of abdominal surgery. Group II was divided into those patients (Group IIa, 13 patients) in whom tuberculosis developed within 10 years after surgery and those patients (Group IIb, 8 patients) in whom tuberculosis developed more than 10 years after surgery. A comparison of chest X-rays showed that the extent of lesions was clearly larger (p < 0.05) in Group IIa than in Group I and that Group IIa required more time (p < 0.05) after treatment was begun until bacterial drainage became negative. Group IIb was clearly older (p < 0.05) than Group I, but the group showed no difference from Group I in the extent of lesions in chest X-rays, and the group required less time (p < 0.05) than Group IIa until bacterial drainage became negative. The patients tended to have an underweight build with average degrees of obesity being -7.5% in Group I, -10.9% in Group IIa, and - 6.7% in Group IIb. Total cholesterol was significantly (p < 0.05) lower in Group IIa than in Group I. One reason why pulmonary tuberculosis was more severe in Group IIa than in Groups I and IIb was probably that the patients had fallen to a low nutritional, underweight condition in the 10 years after their operations, though other factors also need to be considered.