Abstract:[Objective] To investigate the clinical outcomes of blocking screws for hypertrophic nonunion secondary to interlocking in- tramedullary nailing of tibial shaft fracture. [Methods] A retrospective study was done on 34 patients who underwent additional blocking screws for hypertrophic nonunion secondary to interlocking intramedullary nailing of tibial shaft fracture from January 2014 to December 2019. Of them, 15 males and 19 females aged (39.55±10.85) years on average, and suffered closed AO type A in 12 cases, type B in 17 cas- es and type C in 5 cases. The clinical and imaging data of additional blocking screw therapy were summarized. [Results] All the patients were successfully operated on without any serious complications, such as vascular and nerve injury, whereas with operative time of (41.18± 11.53) min, the incision length of (2.09±0.79) cm, intraoperative blood loss of (4.58±2.36) ml, and the intraoperative fluoroscopy of (4.32± 1.25) times. As time went during the follow-up period lasted for (20.21±6.26) months, the VAS score significantly decreased, whereas the knee HSS score and ankle AOFAS score increased significantly (P<0.05) . All patients got nonunion healed in (5.71±1.40) months, except 3 patients were prone to remain fracture nonunion, which finally healed after revision surgery of replacement of a larger diameter intramed- ullary nail and bone grafting. [Conclusion] Additional blocking screw is a minimally invasive, safe and efficient treatment for hypertrophic nonunion secondary to interlocking intramedullary nailing of tibial shaft fracture.