Large femoral neck defects pose a great challenge for orthopedic surgeons and are frequently associated with neglected femoral neck fractures, post infective sequale and failed implants around femoral neck. We present our technique (AIIMS Box Technique) of neck reconstruction aiming to preserve the natural femoral head and restoring the function of hip in cases of large femoral neck defects. A total number of 52 patients (age range 20 to 56 years with an average of 38 years) with large femoral neck defects were treated from January 1990 to May 1997 and were followed for a minimum of 10 years (range 10 to 17 years). Neck defect was converted into a box using osteal flaps (Base from greater trochanter, Anterior wall from head, Quadratus Femoris muscle pedicle graft posteriorly). This box was filled with cancellous bone autograft along with three cancellous screw fixation. Union occurred in all patients in a mean time of 16 weeks (range 12–20 weeks). One patient in our series had avascular necrosis (AVN) of femoral head. Eighteen out of 52 results were classified as excellent, 28 good and 6 fair. No patient had poor result. Good functional mobility including squatting was seen in all but two patients. Complications included coxa vara in two patients, hardware problems in four patients. Our study shows that large femoral neck defects can be managed successfully with preservation of vascularity of femoral head. This procedure can be considered an alternative to excisional or replacement arthroplasty, particularly in young adults.