We established an animal model of radiation-induced skin ulcers in rats irradiated with 35-55Gy gamma-rays. The pathological changes were studied for 1 year. Immunohistochemical studies were performed on 72 radiation-induced skin ulcer specimens using c-erbB-2 and epidermal growth factor receptor (EGF-R) protein antibodies. We found that the overexpression rate of c-erbB2 oncoprotein was 59.7% and of EGF-R was 70.8%. The overexpression of c-erbB-2 was chiefly seen in the activated squamous epithelial cells and in the cytoplasm of fibroblasts, endothelial cells, and leiomyocytes of the arteriolar media in the deep part of the ulcers. The overexpression of EGF-R had the same localizations. It is suggested that the overexpression of c-erbB-2 and EGF-R proteins may be due to the poor healing of the radiation-induced skin ulcers.