Large, full-thickness lip defects after head and neck surgery continue to be a challenge for reconstructive surgeons. The reconstructive aims are to restore the oral lining, the external cheek, oral competence, and function (i.e., articulation, speech, and mastication). The authors' refinement of the composite radial forearm-palmaris longus free flap technique meets these criteria and allows a functional reconstruction of extensive lip and cheek defects in one stage. A composite radial forearm flap including the palmaris longus tendon was designed. The skin flap for the reconstruction of the intraoral lining and the skin defect was folded over the palmaris longus tendon. Both ends of the vascularized tendon were laid through the bilateral modiolus and anchored with adequate tension to the intact orbicularis muscle of the upper lip. This procedure was used in 12 patients. Six patients had cancer of the lower lip, five patients had a buccal cancer involving the lip, and one patient had a primary gum cancer that extended to the lower lip. Total to near-total resection (more than 80 percent) of the lower lip was indicated in six patients. In two other patients, the cancer ablation included more than 80 percent of the lower lip and up to 40 percent of the upper lip. A radial forearm palmaris longus free flap was used in all cases for reconstruction of the defect. Free flap survival was 100 percent. At the time of final evaluation, which was 1 year after the operation, all patients had good oral continence at rest (static suspension) and had achieved sufficient oral competence when eating. Ten patients were able to resume a regular diet, and two patients could eat a soft diet. All patients regained normal or near-normal speech and had an acceptable appearance. The described refinement of the composite radial palmaris longus free flap technique allows the reconstruction of the lower lip with a functioning oral sphincter; the technique can be recommended for patients who need large lower lip resection. It provides functional recovery of the reconstructed lower lip synchronizing with the remaining upper lip.