Sixty-five patients with neoplastic diseases of the larynx, oral cavity, pharynx, and skin have been treated with PDT with followup to 56 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. Eight patients with T2 and T3 carcinomas treated with PDT obtained a complete response, but they all recurred locally. This is due to the inability to adequately deliver laser light to the depths of the tumor bed. five patients with massive neck recurrences of squamous cell carcinomas were treated with intraoperative adjuvant PDT following tumor resection. Only one developed recurrence with 24- month followup. PDT is highly effective for the curative treatment of early carcinomas (CIS, T1) of the head and neck. Also, intraoperative adjuvant PDT may increase cure rates of large infiltrating carcinomas of the head and neck.