Intraoperative I-125 seed implantation for extensive recurrent head and neck carcinomas. From 1978 to 1988, 41 patients with extensive recurrent carcinomas of the head and neck were treated with surgical resection plus intraoperative iodine-125 seed implantation. Surgery was performed to resect the tumors and to expose the tumor beds for implantation. I-125 seeds were implanted intraoperatively, with a spacing of 0.75-1 cm between adjacent seeds, either into the soft tissue in the tumor bed or onto small patches of gelatin sponges to cover the bone, nerve, or blood vessel involved with disease. Reconstructive flaps were used in 18 patients. The average I-125 dose delivered by the implanted seeds was 8,263 cGy. The determinate 5-year actuarial survival rate for the entire group was 40%. The 5-year local disease control rate was 44%. Major complications were transient wound infection (32%), flap necrosis (24%), fistula formation (10%), and carotid blowout (5%). These results indicate that surgical resection plus I-125 seed implantation provides a potentially curative treatment for patients with extensive recurrent head and neck carcinomas that would be considered traditionally unresectable and that would be treated only with palliative therapy. 