Aim: clinical evaluation of diaphyseal femoral fractures operated in lateral decubitus position with interlocking nail. Methods: A prospective observational was conducted in the Department of Orthopaedics, A.N. Magadh Medical College and Hospital, Gaya, Bihar, India for 1 year. Total 50 Patients with age group >18 years and diaphyseal femoral fractures (all types of closed/open diaphyseal variants). Assessment at regular intervals was done at 2, 4, 6, 8 and 12 weeks. At each followup visit, patient was evaluated clinically, radiologically if needed and complications were noted. Results: In our study transverse (46%) was most common fracture pattern followed by Oblique fractures (26%), Oblique- transverse fractures 18%) and spiral fractures (10%). In our study 23 (46%) patients had Fluoroscopy time of 3.5-4 mins followed by 19 (38%) patients with Fluoroscopy time of 2.5-3 mins and 8 (16%) patients with Fluoroscopy time of 3-3.5 mins. The mean Fluoroscopy time was 3.26 mins. There were complications in 4 patients. 1 (2%) patient had limb length shortening by 1.5 cms, 1 (2%) patient had non-union and restriction of movement, 1 (2%) patient had delayed union and 1 (2%) patient had deformity ER and valgus deformity. For evaluation of results in our study Thoresen classification system was used. 58% patients had excellent results with full, pain-free, function of the extremity, 28% patients had good result, 12% patients had fair result and 2% patient had poor result. Conclusion: Operating in lateral decubitus position significantly decreases operative time, fluoroscopy time and blood loss which further helps in early mobilization and weight bearing also allows resumption of knee range of movement exercises at early stage; so it is possible to give good knee range of movement at the end with decreased hospital stay.