Photodynamic therapy (PDT) is a relatively new method of treating superficial tumours of the skin and mucosa. After the injection of a photosensitising agent, the tumour area is exposed to non-thermal laser light. This causes a phototoxic reaction, producing oxygen radicals that destroy tumour cells. From November 2003 to July 2007, a total of 35 patients with recurrent squamous cell carcinoma or secondary tumours of the head and neck region were treated with PDT at the German Armed Forces Hospital in Ulm. These patients had failed or found unsuitable for other treatments. Meta-tetrahydroxyphenylchlorin (mTHPC), known under the trade name of Foscan^®, was used as the photosensitising agent. Local control was achieved in 21 patients (60%) and partial remission in 10 patients (28.5%). Four patients (11.5%) did not respond to PDT treatment. The mean duration of overall survival was 401.45 (±321.2) days, median was 356 after the completion of treatment. The mean duration of recurrence-free survival was 327.7 (±131.1) days, median was 181 for patients with complete remission. None of the patient developed serious complications. Photodynamic therapy is an important treatment option for patients who present with recurrent carcinoma or secondary tumours of the upper aerodigestive tract and who have failed or unsuitable for other treatments. Due to the excellent treatment results that have been achieved so far, PDT may in the future also play a role in the primary treatment of superficial tumours of the oral cavity, pharynx and larynx.