Photodynamic therapy is an effective curative treatment for early carcinomas of the head and neck and may be of benefit as an adjuvant intraoperative therapy to increase cure rates of large head and neck tumors. Eighty-seven patients with neoplastic diseases of the larynx, oral cavity, pharynx, and skin have been treated with photodynamic therapy (PDT) with follow-up to 66 months. Patients with carcinoma-in-situ and T1 carcinomas obtained a complete response after one PDT treatment. All but two have remained free of disease. Ten patients with massive neck recurrences of squamous cell carcinomas were treated with intraoperative adjuvant PDT following tumor resection. Only three developed recurrence with 40-month follow-up, but only one recurrence was in the field of surgery and PDT.