Objective: LIF is a 45-56 kDa glycoprotein that has important role in proliferation and embryo implantation. LIF affcts its function via its receptors such as gp130. Effects of LIF in oocyte matuiration and expression of its receptor in oocytes is unknown. Materials and Methods: Immature mice superovulated with HMG and GV oocytes obtaind from ovary 48 hours after. The GV oocytes were cultured in TCM199 with 5% Co2 for obtaining MII oocyte. For Real-time RT-PCR Total RNA from GV and MII oocytes were extracted by Trizol reagent the quantity and quality of RNA were determined by spectrophotometry and electrophoresis respectively.Reverse tranh1ion was performed by SuperScript III reverse tranh1ase with 1 µg of total RNA followed by DNaseI treatment and heat inactivation. Expression of gp130 was determined by Real time RT-PCR. Results: Our results showed that gp130 is expressed neither in GV nor in MII oocytes during in vitro maturation of mouse oocytes. It is proven that gp130 is expressed in human oocyte but is not expressed in mouse oocytes. Conclusion: It is suggested that in mouse LIF could affects the oocyte via another receptor. However its details must be elucidated.