Abstract: objective Potential roles of the C-ERBB2 protooncogene in contributing to mouse oocyte maturation and in conducting Epidermal Growth Factor (EGF) promoteing mouse oocyte maturation in vitro were investigated. Methods This research used mouse oocyte culture model and RT-PCR method to study the effects of both C-ERBB2 and EGF on mouse oocyte maturation in vitro, and the potential role of the C-ERBB2protooncogene on EGF effect. Results C-ERBB2 ASODN inhibited the rate of germinal vesical breakdown(GVBD) and the first polar(PBⅠ) extrusion of denuded oocytes(DOs) in a dose-dependent and time-dependent way, and delayed their maturation significantly. C-ERBB2ASODN also inhibited the effect of EGF on oocyte maturation in a time-dependent way. In GVBD oocytes, RT-PCR showed that C-ERBB2mRNA was expressed in oocytes and the level of C-ERBB2mRNA was the highest in EGF treated group, midst in EGF+c-erbB2ASODN treated group, and lowest in C-ERBB2 ASODN treated group. Conclusions Our results indicate that C-ERBB2 exists in the oocyte and has promoting effect on oocyte maturation in vitro. EGF plays a role in inducing denuded oocyte maturation through up-regulating C-ERBB2expression of oocyte. Interfering C-ERBB2 expression can reduce the effect of EGF on oocyte maturation.