BACKGROUND AND OBJECTIVE: The fractures of the shaft of humerus are one of the commonest fractures found and can be treated by different methods. The present study is undertaken to know the functional outcome following the use of flexible nails for humeral shaft fractures in adults. MATERIALS AND METHODS: It is a prospective study which was carried out NMC, Sasaram, Bihar. In this study period 20 cases of fracture shaft of the humerus were treated by closed reduction and internal fixation using flexible nails. RESULTS: In our series, majority of the patients were males, middle aged, with road traffic accidents being the commonest mode of injury, involving middle third. INTERPRETATION /CONCLUSION Flexion intramedullary nailing done by retrograde technique produces equally good results comparable to any plate osteosyntehsis or interlocking intramedullary nailing. Another added advantage of flexible nail fixation is it requires very minimal operative instrumentation.