A retrospective review was performed on 46 unstable femoral neck fractures in osteoporotic elderly patients. They were treated with internal fixation using a nail-plate associated with filling of the metaphysis with a biomaterial - natural coral - which undergoes bone incorporation. From 1992 to 1996, the increased knowledge for use of natural coral in the surgical procedures allowed a progressively decrease in the mean time to weight bearing, starting from 26.3 days (1992) to 11.2 days (1996). Primary stabilization at the fracture site was obtained in 42 patients (91.3%), clinically evidenced by the absence of pain from unlimited weight bearing. Only four mild impactions were reported. Consolidation was observed in all cases but one. Among them, more than half of the patients (53.3%) had a time to consolidation equal or lower than to 45 days; 70% healed in 2 months. Biocompatibility of the coral was perfect. Full bioresorbability was observed-partially in five cases, in all other cases from 3 to 18 months. The biomaterial was filled with bone marrow. It acts "as if" it was a real autologous graft. A mechanically perfectly stabilized fracture site, a large amount of biomaterial, a spheric shape, 4 mm diameter, injected with bone marrow, filled in a good environment, are the best conditions to obtain good result with an easily reproducive system.