PURPOSE: We studied the relationship between angular deformity and possibly contributing factors in the treatment of tibial fractures with interlocking nailing. MATERIALS AND METHODS: Intramedullary nailing of the tibia was performed on 49 cases and were followed for the minimum of 12 months. We analyzed relationship between angular deformity and postoperative tibial alignment, operative technique and other factors. RESULTS: Of the 49 cases, 19(38%) were angulated. Angular deformity was seen in 60%, 51.8% and 11.8% in the proximal, distal and middle third of tibial fractures respectively. With AO classification, Group A,B,C were angulated in 32.4%, 55.6%, 66.7%. In group A, 43.8% of spiral fractures, 28.6% of oblique fractures and 14.3% of transverse fractures were angulated. The cases combined with fibular fracture showed higher incidence of angular deformity than the cases with intact fibula. The opening of fracture and the nail insertion site were not significant to angular deformity. CONCLUSION: Angular deformity of interlocking nailing in tibial fractures were more common in proximal, comminuted and spiral fractures. Precise attentions to operative technique i. e. accurate anatomical reduction and centromedullary nail orientation are recommended to prevent angular deformity. In proximal third tibial shaft fractures where muscles and patellar tendon has deforming force on fracture fragment, authors believe that use of interlocking nailing must be limited with fracture pattern.