Objective: To evaluate the effects of bFGF on proliferation and differentiation of rat cochlear sensory epithelial cells. Methods: Cochlear sensory epithelial cells of neonatal rats were isolated and cultured with different bFGF concentration. Bromodeoxyuridine (BrdU) labeling and immunohistochemical staining with calretinin were used to identify mitotic status and properties of culture cells. Results:① In 100 ng/ml and 200 ng/ml bFGF group,the BrdU positive cells were 36% and 35%,respectively,while in 1 ng/ml and 10 ng/ml bFGF group,the BrdU positive cells were only 3% and 7%. ② Percentage of calretinin positive cells varied from 0.5%,1.6%,7%,and 7.6% in 1 ng/ml,10 ng/ml,100 ng/ml,and 200 ng/ml bFGF,respectively. The percentage of the BrdU-positive and calretinin-positive cells in high bFGF concentration groups (100 ng/ml and 200 ng/ml) were significantly different compared with the control group. Conclusion: Proliferation and differentiation of cochlear auditory epithelial cells can be regulated by bFGF.