Photodynamic therapy (PDT) was studied in the treatment of a variety of solid malignant tumors. Ten patients with oral squamous cancers treated by PDT are reported: The laser beam was introduced into the malignant and metastatic lymphatic tissues through inserted optic fibers. The results showed that all the lesions gave complete response to PDT except the bony involvement. It was noted that the lymphatic metastatic foci showed a higher photosensitivity, and the covering skin, connective tissue and the nearby organs were not obviously injured. Combination of PDT with chemotherapy, radiotherapy and surgery are also discussed.