Objective: To investigate the correlation between epidermal growth factor (EGF)/testicular epidermal growth factor receptor (EGF-R) and spermatogenesis in rat. Methods: Forty mature male Spraque-Dauley (SD) rats were randomly assigned to four groups, ten rats in each: sham operation group (SOG), sialoadenectomy group(SG), sialoade-nectomy group with injection of EGF (0. 25 μg·kg-1·d-1, SG-EGF Ⅰ) and sialoadenectomy group with injection of EGF (0. 50 μg·kg-1·d-1 , SG-EGF Ⅱ). The rats were routinely feed, and blood and testes were obtained on the 48th day after the operation. Serum EGF concentrations were determined by radioimmunoassay (RIA) , expression of EGF-R in testes was examined by the immunohistochemical method, and the spermatogenesis was pathologically checked. Results: Serum EGF levels in SG-EGFIand SG decreased significantly when compared with those of SOG (P<0. 05 and P< 0. 01, respectively). The testicular function of spermatogenesis showed a moderate to severe impairment in SG. The expression of EGF-R in Leydig cells decreased in SG(P<0. 05). The two dosage groups of EGF replacement had different effects. There were no significant differences of EGF-R expression in testicular germ cells, Sertoli cells and Leydig cells in SOG, SG-EGFⅠand SG-EGFⅡ(P>0. 05). Conclusion: EGF may play an important role in the regulation of spermatogenesis. Serum EGF concentration and high expression of EGF-R in Leydig cells have a positive correlation with spermatogenic function of the testes. Methods: Forty mature Spraque-Dauley (SD) rats were randomly assigned to four groups, ten rats sialoadenectomy group (SG), sialoade-nectomy group with injection of EGF (0. 25 μg · kg-1 · d-1, SG-EGF Ⅰ) and sialoadenectomy group with injection of EGF (0.50 μg · kg-1 · d-1, SG-EGF Ⅱ). The rats were routinely fed, and blood and testes were obtained on the 48th day after the operation. Serum EGF concentrations were determined by radioimmunoassay (RIA) , expression of EGF-R in testes was examined by the immunohistochemical method, and the spermatogenesis was pathologically checked. Results: Serum EGF levels in SG-EGFI and SG decreased significantly when compared with those of SOG (P <0. 05 and P <0 . 01, respectively). The testicular function of spermatogenesis showed a moderate to severe im The expression of EGF-R in Leydig cells decreased in SG (P <0.05). The two dosage groups of EGF replacement had different effects. There were no significant differences of EGF-R expression in testicular germ cells, Sertoli cells and Leydig cells in SOG, SG-EGF I and SG-EGF II (P> 0.05). Conclusion: EGF may play an important role in the regulation of spermatogenesis. Serum EGF concentration and high expression of EGF-R in Leydig cells have a positive correlation with spermatogenic function of the testes.