For a study, the researchers wanted to look into reoperation cases and see if a single surgeon’s experience was linked to the reasons for reoperations after lumbar microendoscopic discectomy for disc herniation (MEDH) and microendoscopic decompression for spinal stenosis (MEDS). Only a few researchers had looked into cases of reoperation after MEDH and MEDS. The same surgeon used MEDH and/or MEDS on 441 consecutive patients between June 2005 (first experience with MEDH) and September 2013. The percentage of follow-up was 89.3%. At 5 years following the first operations, the causes and rates of reoperations (RORs) were determined. The researchers also looked into a single surgeon’s experience period (EPS, the interval between June 2005 and initial operation: median, 37 months). For all patients combined, the 5-year reoperation rate was 12.4% (49/394). Recurrence of disc herniation (ROR, 7.01%) and increased postoperative spondylolisthesis and/or instability (ROR, 9/394=2.28%) were the most common reasons for reoperations; two of the nine instances were caused by excessive decompression, with EPSs of 11 and 16 months. Postoperative epidural hematoma (ROR, 0.76%; median EPS, 20 months), insufficient decompression (ROR, 0.25%; EPS, 17 months), and residual segmental scoliosis (ROR, 7.69%) were the other reasons for reoperations. About 2 cases of residual segmental scoliosis did not provide relief from sciatica, so L4/5 transforaminal interbody fusions were performed. Reoperations were frequently seen in the initial group of patients due to postoperative epidural hematoma and excessive or inadequate decompression. Because there were limitations to any surgical indications for the use of microendoscopic decompression for degenerative segmental scoliosis because of original traction and/or kinking of nerve roots, the researchers believed it was important to be aware of and prevent such potential problems in an initial series of patients.