Chemotherapy, surgical therapy, and radiotherapy are the methods currently employed for treatment of oral cancer. For the oral cavity, however, extensive surgery and radiotherapy face considerable limitations because its anatomical complexity. Also, speedy healing of wounds is desirable and restoration of the morphology and functions must be achieved as early as possible. It is therefore important in the postoperative chemotherapy to prevent local recurrence and metastasis by keeping the side effects of anticancer agents to a minimum and providing an extended administration of the agents. Wounds were experimentally made in the tongue in domestic rabbits and the effect of anticancer agents (Bleomycin and Mitomycin C) on the healing process was investigated histopathologically and histochemically. The results were as follows : I. Histopathological findings A. In Bleomycin group (3.0mg/kg/day), with increase in the number of administration, proliferation and maturity of epithelial cells, granulation tissues, and fibroblasts were retarded and healing of wounds in the epithelial layer in particular was retarded markedly. B. In Mitomycin C group (0.5mg/kg/day), with increase in the number of administrations, epithelialization of the epithelial layer and proliferation and maturity of granulation tissues and fibroblasts under the epithelial layer were retarded. II. Enzyme-histochemical findings A. In Bleomycin group, along with the retardation of healing wounds in the epithelial layer, Lactate Dehydrogenase (LDH), Succinate Dehydrogenase (SDH), Alkaline Phosphatase (ALP), Acid Phosphatase (ACP) and Non-specific Esterase (EST) gradually decreased in reaction. About in coincidence with the proliferation and maturity of granulation tissues and fibroblasts, LDH, ALP, ACP and EST decreased in reaction. SDH however did not show much change in reaction. B. In Mitomycin C group, along with the retardation of proliferation and maturity of fibroblasts and granulation tissues, LDH, SDH, ALP, ACP and EST decreased in reaction. However, decrease in reaction of each enzyme in the new epithelial layer was relatively slight. C. The foregoing changes in enzyme reactions were especially marked in the epithelial layer, granulation tissues, and the layer of fibroblasts, and the reactions increased with increase in the number of administration. In comparison with the control group, however, the reactions decreased markedly. Also, these changes about coincided with the histological retardation of healing wounds. III. On the basis of the foregoing experimental results, administration of Bleomycin and Mitomycin C in the healing process of tongue wounds not only retarded healing of wounds because of proliferation and maturity of epithelial cells and granulation tissues but also decreased enzyme reactions of oxidase and hydrolase. Their administration therefore was thought strongly affect the functions of mitochondria related with wound healing, maturity of collagen, metabolic mechanism of cells such as functions of lysosome.