Photodynamic therapy (PDT) utilizing Photofrin has proven to be an effective modality used in the treatment of solid tumors. In particular, it can be applied via endoscopy to lesions developing in luminal organs. A phase II study was conducted for submission to the Japanese Ministry of Health and Welfare. In this protocol an excimer dye laser was used to deliver 630 nm light via a quartz fiber passed through an endoscopic working channel two days subsequent to i.v. injection of photosensitizer. In this study, 98 patients with superficial cancer of various organs were treated. Of these, 88 patients could be evaluated, including 33 with roentgenographically occult lung cancer, 10 with esophageal cancer, 24 with gastric cancer, 18 with cervical cancer and three with bladder cancer. Complete remission as evaluated endoscopically, pathologically, and cytologically was obtained in 83 out of 98 (84.7). There was no serious complication except mild skin photosensitivity, which was seen in four patients. It was concluded that PDT can be efficacious in the treatment of superficial cancers and that complete remission can be achieved when suitable photoradiation conditions are met.