The analysis of the complications of the pectoralis major osteomyocutaneous flaps used for head and neck reconstruction and how to prevent them is the subject of this report. Ten patients with squamous cell carcinoma of the floor of the mouth who had undergone segmental glossectomy and mandibulectomy, radical uni-or bilateral cervical lymphadenectomy, and immediate reconstruction with the pectoralis major osteomyocutaneous flaps were evaluated. Neither partial nor total necrosis of the myocutaneous segment occurred in any patient but rib necrosis developed in five. An oral fistula occurred in four patients exposing the junction of the rib with the mandible. There were three cases of flap necrosis of the neck dissection. Two patients developed pneumothorax. The overall complication rate was 66.7%. Although this surgery requires major intraoral excision, the tumor is exophytic with previous infection and the patients' general condition debilitated, the incidence of complications is high. Despite the high morbidity, the pectoralis major myocutaneous flap remains a useful adjunct for head and neck reconstruction. The flap is versatile and for many patients repair with a free flap is impossible because of contraindications such as previous irradiation, problems with the vascular anastomoses, advanced age and poor general condition. It also aids in the surgical training of new specialists.