Purpose:We analyzed the patients who needed reoperation after undergoing a thoracolumbar spine operation and investigated the causes, pattern of timing, medical history and clinical outcome after reoperation. Materials and Methods: Out of 2,198 patients who underwent spine surgery for thoracolumbar spine disease from 1988 to 2011, we targeted 193 patients who underwent reoperation. We studied the causes, operative method of initial surgery, time-variant causes and outcome of reoperation. Results: The number of patients who underwent thoracolumbar spine reoperation was 193 out of 2,198 and the reoperation rate was 8.7%. We researched time-variant causes of reoperation. In six weeks after the initial operation, exploration for hematoma and neurologic deficit was 18 (26.8%), recurred heniated intervertebral disc (HIVD) was 18 (26.8%), and surgical site infection was 17 (25.4%). From six weeks to six months, recurred HIVD was 10 (47.6%), surgical site infection was 7 (33.3%), and after six months, adjacent segmental disease (ASD) was 38 (35.7%), recurred HIVD was 26 (23.2%), and implant related problem was 17 (16.0%). Conclusion: Causes of thoracolumbar spine reoperation included complications (2.8%); infection, hematoma, neurologic deficit, incomplete decompression, and natural courses (5.9%); ASD, recurred HIVD, implant related problem, instability after decompression, tumor recur, progression of deformity.