This retrospective study aimed to compare the patient-reported outcomes and radiographic assessment of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) for degenerative spondylolisthesis with reduction versus in situ fusion. Patients receiving MI-TLIF with reduction were assigned as Group A, and those without reduction were assigned as Group B. Radiographic fusion was assessed using Bridwell's grading criteria. Preoperative and postoperative patient-reported outcomes including visual analogue score (VAS), Oswestry Disability Index (ODI), Japanese Orthopedic Association (JOA) scale and improvement rate were analyzed. There were 41 patients in Group A and 37 patients in Group B. The mean follow-up was 30.78 +/- 14.15 months in Group A and 28.95 +/- 10.75 months in Group B (p = 0.525). There were no significant differences in hospital stay (p = 0.261), estimated blood loss (p = 0.639), blood transfusion (p = 0.336), operation time (p = 0.762) and complications (p = 1.00) between the two groups. Radiographic fusion rate was 92.68% (38/41) in Group A, and 81.08% (30/37) in Group B (p = 0.110). Significant differences were observed in either 3-month or last follow-up JOA, VAS, and ODI compared with preoperative JOA, VAS, and ODI, respectively (p < 0.05). However, there were no significant differences in JOA, VAS, and ODI between the two groups whenever preoperatively, or 3 month postoperatively, or at the last follow-up (p > 0.05). According to MacNab criteria, the excellent and good rate was 85.37% in Group A and 86.49% in Group B (p = 0.983). MI-TLIF is an effective and satisfactory surgical technique to manage degenerative spondylolisthesis regardless of reduction or not, so routine reduction may not be a requirement in MI-TLIF for degenerative spondylolisthesis. (C) 2016 Elsevier Ltd. All rights reserved.