Background: Tibial shaft fractures were common occurrence due to road traffic accident, most casualty affecting the active working people, male were more affected than female. Treatment of diaphyseal fractures were treated by close reduction and internal fixation with interlocking intramedullary nail showed in many study with excellent results. Objective: To evaluate and analyze the results and outcome of tibial shaft fractures by interlocking intramedullary nail. Methods: This prospective observational study (case series) was conducted in the department of orthopaedic and traumatology department, Dhaka Medical College and Hospital and NITOR from January 2011 to December 2012. This study included both sexes and age between 18 years to 55 years and 30 patients were included in this study. As per inclusion and exclusion criteria all stable or non-displaced unstable or displaced and Gustilo type-1 fractures of proximal, middle and distal third fractures were included in this study .Diagnosis of the tibial diaphyseal fracture was made by history, clinical examination & radiological evidence. Results: A total number of 30 patients were treated and followed up in this study. Among 30 patients 21 (70%) were male and 9 (30%) were female, mean age was 31.8 years with a range of 18 years to 55 years median was 32.5 years mode was 34 years and SD was 2.1. in the study mode of injury distribution was 21 (70%) RTA, 6 (20%) fall from height and 3 (10%) assault. In this study severity injury 46.7% are stable 33% are unstable and 23.3% was Gustilo-1 , distribution of level of fracture was middle third 57% distill third 29% and proximal third 17% , injury surgery interval average 11.5 days (60%) in 18 cases and 5 days (40%) in 12 cases. Partial weight bearing given at 2 weeks & full weight bearing at 6 weeks and union occurred in average 18.5 weeks. In rating of final outcome 24 cases (80%) were excellent, 3 cases (9%) were good, 2 cases (7%) were fair and 1 case.......