This study compared the clinically usable bone regions of the ilium and fibula for mandible reconstruction. Measurements were taken of 241 ilia, 91 mandibles, and 60 fibulas. The ilium offered a similar total usable bone length to the fibula but maintained a more constant bone thickness throughout, whereas the fibula's dimensions varied significantly. In some fibulas, only a small portion of the total bone length could actually be used. The study suggests the ilium may be a better donor site than the fibula, especially for women requiring occlusal rehabilitation after mandible reconstruction.