When vascularized fibula grafts are used in mandibular reconstruction, it is often necessary to divide the graft into segments so as to follow the mandibular curvature, The periosteal blood supply to the segments is usually sufficient. It is unclear, however, how short the segments can be without compromising the blood supply The present study sought to clarify this issue by injecting Indian ink into the efferent vessels in human cadavers. The evaluation of 300 specimens showed the ink perfusion to be significantly higher in segments longer than 1 cm than in shorter segments, Furthermore, the perfusion in the cortical outer third of the shaft was markedly higher than in the cortical inner two-thirds. The staining was significantly more intense in the younger (32-55 years) than in the older (56-73 years) age group. With correct dissection and successful anastomosis, however, fibula segments 1 cm or longer are probably sufficiently perfused, independent of the patient's age, The perfusion in shorter segments is uncertain. Clinically this means that segments shorter than 1 cm ought to be used only in a surgically noncompromised recipient site, where they could also take as non-vascularized grafts.