Objective:To observe the expression of epidermal growth factor (EGF) and its receptor (EGFR) in the body fluids and renal tissues of rats with autosomal dominant polycystic kidney disease (ADPKD) and to explore their roles in the development of the disease.Methods:EGF levels in the blood and urine of Han:SPRD rats were determined by ELISA. Western blotting,in situ hybridization and immunohistochemistry were used to examine the expression of EGF/EGFR in the kidneys of ADPKD rats. Results:The concentration of EGF in the urine was higher than that in the blood. EGF level in the body fluids of 3 weeks old rats was higher than that of the 3 months old rats. The urine EGF level of cy/+ rats was significantly lower than that in the normal rats (\[263.45±48.53\] pg/ml vs \[321.09±74.57\] pg/ml,P<0.05). The renal distribution pattern of EGF remained unchanged in rats with ADPKD,but the expression level was down-regulated. EGFR in ADPKD rats was ectopically overexpressed on the apical and basolateral membrane of cystic cells. The order of EGFR and phosphorylated EGFR expression was: cy/cy rat> cy/+ rat> +/+rat.Conclusion:The abnormal EGF/EGFR might play a key role in the development and progression of the ADPKD.