The long term fate of the fibula in an intra-osseous site is still a matter of debate. Since the procedure of free fibular grafting for neglected femoral neck fractures was routinely done at our institute, we were able to observe the serial changes in 37 cases with an average 8.9 years follow-up. Graft incorporation was not consistent in the 4 to 10-year postoperative period, but in cases with more than 10 years follow-up, a major portion of the graft got incorporated into the host bone. A classification system for the incorporated grafts is suggested. The presence of avascular necrosis seems to initially hinder graft incorporation, but if the bone revascularises, graft incorporation proceeds at a comparable rate. This study shows that cortical bone gets well incorporated into host cancellous bone and helps to reconstitute the neck in cases of femoral neck nonunions.