Local or regional flaps usually are sufficient for reconstruction of defects of the cranial base. In some cases, however, free-tissue transfer may be the best or the only choice. Reasons for choosing free-tissue transfer over other methods of reconstruction include previous radiation, previous surgery, limited arc of rotation of pedicle flaps, lower complication and failure rates of free flaps, and specific tissue requirements that only can be met with a free flap. The anatomy, available flap choices, indications, and technical considerations applicable to cranial base reconstruction with microvascular surgery are discussed.