Background: Although reconstruction of anterior mandibular oncologic defects with bony free flaps is considered the standard method of treatment, the optimal reconstruction of posterior defects is controversial. The authors' goal was to compare outcomes using either a vascularized bone flap or a soft-tissue free flap for posterior mandibular reconstruction. Methods: Data were collected prospectively on 74 patients undergoing posterior mandibular resection including the condyle. Results: Twenty-four patients underwent vascularized bone flap reconstruction and 50 patients underwent soft-tissue free flap reconstruction. Patients undergoing vascularized bone flap reconstruction were significantly younger than those undergoing soft-tissue free flap reconstruction (47 versus 62 years, respectively; p = 0.0001) and had a lower American Society of Anesthesiologists class (2.6 versus 3.1, respectively; p = 0.001). There were no significant differences in total operative time, intensive care unit stay, or hospital stay. The complication rate was 33 percent for patients receiving vascularized bone flap reconstructions and 38 percent for patients receiving soft-tissue free flap reconstruction (p = 0.70). Mouth opening averaged 39.8 mm for patients with vascularized bone flap reconstructions and 46.4 mm for patients with soft-tissue free flap reconstructions (p = 0.09). Jaw deviation toward the resection side averaged 1.2 mm for vascularized bone flap reconstructions and 5.3 mm for soft-tissue free flap reconstructions (p = 0.02). There was no significant difference in the type of mechanical diet tolerated by either group (p = 0.83). Conclusions: With careful selection, good reconstructive results after posterior mandibular resection can be achieved with vascularized bone flap or soft-tissue free flaps. In appropriate candidates, vascularized bone flap reconstruction may result in better postoperative occlusion.