Introduction: Sub-trochanteric fractures of the femur remains one of the most challenging fractures faced by orthopaedic surgeons. This study was done to analyse the management and complications of sub-trochanteric fractures using long proximal femoral nail (PFN).Materials and Methods: This was a prospective study of 50 patients with sub-trochanteric fractures of femur who were treated with long PFN at a tertiary care center from July 2012 to June 2016. The fractures were classified according to Seinsheimer classification. All patients were assessed functionally by Harris Hip Score.Results: Average duration of union was 17.08 weeks (range 13 to 32 weeks), union was achieved in 92% cases. Closed reduction was achieved in 68% cases and open reduction was required in 32% cases. Various intraoperative complications were seen in 12% and delayed complications in 26% of cases. Good anatomical results were achieved in 86% of cases and 14% were fair. As per Harris Hip score, excellent results were noted in 28% cases, good in 56% cases and fair in 16% cases.Conclusion: The long PFN is a reliable implant for subtrochanteric femur fractures, with high rate of bone union and minimal soft tissue damage. Intramedullary fixation has biological and biomechanical advantages, but the surgery is technically demanding.