Magnetic resonance angiography (MRA) is currently considered the most useful test to evaluate the vascular anatomy of the lower leg prior to free fibula osteocutaneous flap transfer. This study aimed to confirm the validity of preoperative MRA. Methods: In 19 patients underwent free fibula osteocutaneous flap transfer for maxillary and mandibular reconstruction, the MRA and intraoperative findings and the postoperative complications were retrospectively analyzed. The location and number of distal septocutaneous perforators (dSCPs) that were preoperatively identified and harvested with flaps were documented. Results: Preoperative MRA detected dSCPs with 100 % sensitivity. MRA findings also revealed the diversity of vascular structures, such as the tibio-peroneal bifurcation location and the anatomical relationship between the peroneal vessels and the fibula. No patients suffered postoperative ischemic complications in the donor leg. The total flap survival rate was 95 %. Conclusions: Preoperative MRA effectively excluded large vessel anomalies and peripheral vascular disease, and precisely identified the septocutaneous perforators. Additionally, preoperative MRA contributed to a safer fibular osteotomy by predicting the anatomical relationship between the peroneal vessels and the fibula. © 2013 Wiley Periodicals, Inc. Microsurgery 33:454–459, 2013.