Cancer, when detected at an early stage, has a very good probability of being eradicated by surgery or radiotherapy. However, less aggressive treatments also tend to provide high rates of cure without the side effects of radical therapy. We report on the results of our clinical experience with photodynamic therapy (PDT) for the treatment of early carcinomas in the upper aerodigestive tract, the esophagus, and the tracheobronchial tree. Sixty-four patients with 101 squamous cell carcinomas were treated with three different photosensitizers: hematoporphyrin derivative (HPD), Photofrin II, and tetra (m-hydroxyphenyl)chlorin (mTHPC). Seventy-seven (76%) tumors showed a complete rsponse with no recurrence after a mean follow-up period of 27 months. There was no significant difference in terms of cure rates among the three dyes. However, mTHPC has a stronger phototoxicity and induces a shorter skin photosensitization than either of the other photosensitizers. There were eight major complications: three esophagotracheal fistulae after illumination with red light in the esophagus, two esophageal stenoses following 360 degrees circumferential irradiation, and three bronchial stenoses. Illumination with the less penetrating green light and the use of a 180 degrees or 240 degrees windowed cylindrical light distributor render the risk of complications in the esophagus essentially impossible, without reducing the efficacy of the treatment. Therefore, PDT may be considered as a safe and effective treatment for early carcinomas of the upper aerodigestive tract, the esophagus, and the tracheobronchial tree.