A review of nine cases who developed reactivation of residual foci in the ipsilateral lung after pulmonary resection was given. The incidence was 1.3 per cent among 700 resections for pulmonary tuberculosis performed in National Okayama Sanatorium up to 1956. Following results were obtained. 1) Reactivation occurred between from 8 months to 2 years and 2 months after surgery. Conversion to positive sputum was noted earlier than the changes in roentgenogram in most cases. 2) All had cavitary diseases for which resection was done and most of them discharged strongly positive sputum before surgery. 3) Chemotherapy before resection was short term with small doses in most cases except the last four who had relativery large amount of antimicrobial drugs during postoperative priod. None of five cases where sensitibity test to antituberculous drugs were made, developed resistancy to more than two kinds of drugs. 4) Expansion of the remaining lung was considered to be overexpansion in none of them though expansion of each segment was not uniform but it was marked in the adjacent segment to the resected one. 5) Reactivation of residual foci occurred only in the adjacent segment inspite of that residual foci in the other segment or in the contralateral lung showed improvement in some of them. 6) Reactivations were controlled in two by chemotherapy, one by resection, two by cavitary drainage and two by thoracoplasty. One who was treated by thoracoplasty combined with long term chemotherapy got worse and the other one who was not rehospitalized showed no change.