Total hip arthroplasty (THA) is one of the successful and cost-benefit surgical treatments. One-stage bilateral THA (BTHA) offers many benefits. However, there are concerns about the safety of the procedure and higher complications. We aimed to evaluate the complications and outcomes of one-stage BTHA with Hardinge approach for femoral head avascular necrosis patients. A total of 60 patients from April 2009 and May 2013, were underwent one-stage bilateral total hip arthroplasty (BTHA) in Milad and Erfan hospitals, Tehran, Iran. A prospective analysis of the functional outcomes and complications of one-stage BTHA through Hardinge approach in patients with femoral head avascular necrosis (AVN) performed. We evaluated all patients clinically and radiologically with serial follow-ups. A clinical hip score based upon the modified Harris Hip Score (MHHS) was performed preoperatively and again postoperatively. During period of study 44 men (73.3%) and 16 women (26.6%) with a mean age of 31.40±4.08 years (range 25 to 36 years) at the time of presentation were entered. The mean surgical time was 2.6±0.38 hrs. The mean hospital stay was 3.50±0.72 days. Hemoglobin level decreased significantly after operation (P= 0.046). There was no reported patient with perioperative death, deep venous thrombosis, pulmonary embolism, infection, dislocation, periprosthetic fracture or heterotrophic ossification. The mean preoperative MHHS score was 47.93±7.33 in patients. MHHS score improved to 95.06±3.47 in the last follow-up (P=0.0001).Our results recommend the use of one-stage BTHA through Hardinge approach in femoral head avascular necrosis patients.