Background: Complications of the residual postoperative pleural space (RPPS) after partial pulmonary resections increase hospital stay, cost and morbidity. The objectives of this study were to define and identify the long-term outcome of RPPS. Methods: A total of 140 partial pulmonary resections were performed in a 3-year period. Fifty-eight (41.4%) patients who had RPPS on the first postoperative day were followed up. We examined the chest x-rays of these patients on postoperative day 1 and 7 and week 4 and 12, and we documented any complications and reoperations. Results: RPPS persisted in 6 patients (10.4%) and was reabsorbed in 44 patients (75.8%) in the 12th week. Residual spaces were complicated in 8 patients (13.7%), of whom 4 (6.8%) had reoperation and 4 (6.8%) were redrained. Reoperated patients had a mean of 13 ( standard deviation [SD] 2.4, range 11-16) days of postoperative hospitalization, whereas redrained patients had a mean of 58.5 (SD 21.7, range 36-88) days of additional hospitalization. Conclusions: We determined air leakage and space infection to be the major complications of the RPPS. Infectious complications were noticed in the postoperative third and fourth weeks (14-30 d), and reoperated patients had a shorter duration of postoperative hospitalization. Early operation is recommended in complicated pleural space patients. The space that is not complicated until the end of the first month can be defined as benign. This study demonstrated that follow-up of a benign space after the first postoperative month is not necessary.