To study EGF and EGFR expression during the formation and development of radiation-induced skin ulcers and their effects on ulcer healing, a rat model which was locally irradiated with ,60,Co γ-rays was used, and another rat model of simple skin wounds was made as a control. Pathological changes were observed for 55d. Immunohistochemistry ,in situ, hybridization and image analysis were performed to detect EGF and EGFR expression in the tissue of radiation skin ulcers. Results: Skin ulcers were found on 14d after irradiation, and they were enlarged and deepened gradually during the observation period. In the irradiated skin, especially in the epidermal cells, fibroblasts and endothelial cells in the ulcer beds, the expression of EGF and EGFR was higher than that in normal skin. But their expression was obviously decreased in the radiation ulcer beds compared to that in the surgical wound beds. After irradiation, the decreased expression of EGF and EGFR may play an important role in the formation, development and nonhealing mechanism of radiation skin ulcers.