Multiple osteotomies with the help of 3-dimensional planning have improved the accuracy of reconstructions, and the reliability and versatility of the fibular free flap is well recognised. To investigate the periosteal blood supply of the fibula and to define safe limits for the size of bony segments, we performed a cadaveric study on 10 fresh frozen lower limbs using a combined barium latex mixture. We modelled cuts at intervals of 1.0, 1.5, and 2.0 cm, and assessed the number of periosteal vessels. After virtual dissections using DICOM data obtained from high-resolution computed tomograms (CT), on average we found 12.8 periosteal branches, with a mean (SD) distance between them of 1.36 (0.18) cm. In 34.9% of the 1 cm segments there were no visible periosteal vessels. Vascularity seemed to be more reliable in longer segments, with 83.4% of those 1.5 cm long, and 94% of those of over 2 cm containing at least one branch. (C) 2015 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.