The expression and localization of bFGF and TGF-(beta)[inf 1] in the inner ear of ten 10-29 week human fetuses were studied using the LSAB immunohistochemical technique referred to the method of Shi. The bFGF was strongly expressed in Corti's organs, vestibule macula and ampullar crista. The color of the upper cells of Corti's anlage was a little deeper than that of the basal cells. The hair cells and supporting cells in the matured Corti's organ continued to have distinct expression. Sites such as spiral ganglion (SG) neurons, stria vascularis (SV) had positive expression. Some cartilaginous cells and osseous cells in the developing osseous labyrinthus had light expression. TGF-(beta)[inf 1] was expressed in the epithelium of Corti's organ, vestibule macula, and ampullar crista. Hair cell color had a tendency to become weak with the maturity of the sensory epithelium, SG neurons, SV and spiral prominence (SP) had the TGF-(beta)[inf 1] expression too. The results indicated that bFGF and TGF-(beta)[inf 1] had participated in the course of inner ear development. The bFGF is a strong mitogen. However in this experiment it was found that it had the effect to promote differentiation. TGF-(beta)[inf 1] had double effect of promotion and inhibition on the proliferation and differentiation of cells. The expression of bFGF and TGF-(beta)[inf 1] in SG neurons indicated that both factors had participated in the development of the nervous system of the inner ear.