Completion pneumonectomy refers to an operation intended to remove what is left of a lung partially resected during a previous operation. The procedure is seldom indicated and the risk of operative mortality and morbidity is higher than standard pneumonectomy. Four patients underwent completion pneumonectomy for recurrence of lung cancer. The first patient had metastatic lesion of hilar lymph nodes more than five years after surgery. The second one had received preoperative radiation therapy and the third had very poor pulmonary function. The last one had underwent pulmonary resections twice during twelve years. Each case was relatively uncommon and gave the difficult surgical problem, but all patients survived the operation and are doing well at present.