Background and Objectives: Intramedullary interlocking nailing is currently considered the treatment of choice foropen(grade 1 and grade 2)tibial shaft fractures, with high rates of fracture union, advantages of early stabilization which decreases the morbidity and mortality rates in patients, allows early mobilization, reduces the incidence of infection,malunion,nonunion, or implant failure. This study is done to assess compound diaphyseal fractures of tibia and to evaluate the functional outcome of patients with open tibial shaft fracture treated with locked intramedullary nailing without reaming. Methods: Twenty adult patients of both sexes presented with open tibial shaft fractures to Princess Esra Hospital, Deccan College of medical sciences,Hyderabad who satisfies our inclusion criteria and are surgically fit are included in this study. All enrolled Patients were admitted from March 2020 to December 2021 were treated surgically with locked intramedullary interlocking nailing tibia without reaming and evaluated. Final assessment of functional outcome is done using JOHNER and WRUH’S Criteria. Results: The results of interlocking nail for fracture tibia without reaming were excellent in 15 patients (75%), good in 3 patients (15%) and fair in 2 patients (10%). The average healing time was 20.13 weeks. In our study valgus deformity of 3 degrees (3 patients) and varus deformity of 3 degrees (1 patient) is seen. There were 1 superficial infection (5%), 2 patients with anterior knee pain (10%), 1 patient with delayed union (5%) and 1 patient with shortening of 1cm seen (5%). Conclusion: The method of treatment employing closed intramedullary interlocking nailing without reaming to stabilize open (type 1 and type 2) diaphyseal fractures of tibia is ideal because of its excellent and good results. The method has a long learning curve but with the excellent results. The advantages of rapid rehabilitation and relatively few complications serve to recommend it for wider use.