This is a report of an immediate reconstruction of a composite mandibular defect, using a pectoralis major osteomusculocutaneous flap incorporating a segment of the fifth rib. Viability of the transferred rib segment was established by tetracycline labeling at 2 weeks and technetium scanning at 3 months postoperatively. This clinical example supports the experimental observations of a vascular network interconnecting muscle, periosteum, and compact bone.