In preparation for the donor and recipient facial vascularized composite allotransplant (VCA), the marginal mandibular nerve branch should be identified and co-apted to the recipient's nerve to allow for re-innervation. We describe a method to identify the marginal mandibular branch of the facial nerve in facial VCA donors and recipients. Through cadaver dissections, the posterior facial vein was traced posteriorly to identify the marginal mandibular branch of the facial nerve. In cases where we were unable to use this relationship, we found the posterior facial venous system to be diminutive. This technique is useful for finding the marginal mandibular branch when dissecting anterograde to the parotid gland.