A total of 75 cases of bladder tumors were treated with contact Nd:YAG laser therapy from February 1984 to April 1988. In 14 of 75 cases post-therapeutic total cystectomy was performed and laser irradiated areas were evaluated pathologically. The results were as given below. 1. The irradiated area a was well demarcated from the non-irradiated area and had ulceration and granulation. 2. Ulceration extended to the deep muscle layer but no perforations were noted in any cases. 3. Although intensive edema was present in the fresh granulation, by approximately Post-irradiation week 3 the fibroblast cells and the fibrous cells had appeared and new vascular growth was manifest. A year later very small scarred tissues, distinctly demarcated from the surrounding tissues, appeared or the granulation was absorbed. Carbonized foreign bodies were incorporated in the granulation with the confirmed presence of the giant cells ingesting the foreign bodies. 4. With the exception of two cases where eosinophilic invasion was predominant, neutrophilic infiltration was predominant in the granulation throughout the cases. 5. In cases at Stage T3, the irradiated beds were suspected of having residual cancer cells. 6. Contact irradiation would not be accompanied by transfer of the cancer cells. It was concluded that contact Nd:YAG laser therapy could be safely instituted in the treatment of bladder tumors in which transurethral treatment would be indicated.