Abstract： BACKGROUND: At present, the researches on murine model of acute radiation encephalopathy are still in investigation, and mature model making method is not clear.OBJECTIVE: To establish a murine model of acute radiation encephalopathy in order to provide a good foundation for further researches of radiation encephalopathy(REP) mechanism and therapy.DESIGN: Randomized controlled study based on the experimental animals.SETTING: Animal laboratory in a university hospital. The Second Affiliated Hospital of Sun Yat-sen University.MATERIALS: The experiment was completed in the Laboratory of the Second Affiliated Hospital of Sun Yat-sen University from June 2001 to August 2002. Totally 30 female and 30 male SD rats, weighted(300 ± 30) g, were selected from the Animal Experiment Center of Sun Yat-sen University, and randomly divided into blank control group with 20 rats and experimental group with 40 rats.METHODS: Fourty rats' brain received 60Co γ-ray irradiation with the dosage of 7 Gy/time per day for 6 consecutive days with the total dosage of 42 Gy. The amount of ingestion and drinking, general activities, central nervous system(CNS) symptoms and signs were recorded every day. The hairs and skin of irradiated field and weight were checked and recorded weekly. On the 3rd, 7th, 14th, 30th days after radiation, the brain tissue was collected and the histopathologic changes were examined.Histopathologic changes after radiation.RESULTS: Since the third day, the ingestion and drinking amount of irradiated rats were decreased. The general activities were increased for the first two days, but decreased without abnormal nervous signs on the 3rd day. The rats in experimental group had a slower weight gain than those of control group, and the difference between them was of no statistical significance. All rats had slight alopecia and neuronal necrosis 2 weeks after irradiation.CONCLUSION: The irradiation method is reliable, practical and good for modeling REP process, which can be used in preventing or reducing the harm effect of radiation therapy on brain tissue.