The pectoralis major flap (PMF) is one of the most used pedicled flaps for reconstructive surgery in head and neck. Basing on previous studies observing that a vascular accident or pedicle ligation not always resulted in necrosis of free flaps, sometimes after a short critical period, we describe the possibility to perform the division of the PMF pedicle. The autonomization of PMF is based on the hypothesis that the flap, after a critical period, develops a neoangiogenesis at the free portion in the recipient site. It represents a possible choice in selected patients with relapse or second tumour of the oral floor and/or mobile tongue, who have been already treated with PMF reconstruction. We provide a step-by-step description of the autonomization and use of the modified PMF. Moreover, we reported advantages and pitfalls. The modified PMF represents a safe reconstructive choice for patients advised against a free flap or a second pedicled flap, with good surgical outcomes.