Background & Aim: Considering that antioxidants are known as effective free radicals scavenger, it may be able to improve the in vitro oocyte maturation and the fetal quality. This study was designed to determine the effect of Gundelia tournefortii leaves (GTE) hydro-alcoholic extract as a source of antioxidant on in vitro oocyte maturation. Experimental: Germinal vasicle (GV) were recovered from 6-8 weeks old NMRI ovaries. GV were cultured for 24 hours in maturation medium in MEMα supplemented with 7.5 IU/ml hCG, 100 mIU/ml rhFSH, 5% FCS (control group) and adding different doses of GTE extract (group I: 10 µg/ml, group II: 20 µg/ml, and group III: 40 µg/ml) and then in vitro maturation stages and resumption of meiotic in all groups was recorded by inverted microscope. Results: In group I, maturation rates were improved compared to the control group. But this difference was not significant. In group II, maturation rates showed a significant increase compared to the control group (p<0.05). In group III, also maturation rates showed a significant increase compared to the control group (p<0.05). Recommended applications/industries: The results of this study showed that the extract from Gundelia tournefortii leaves has a positive effect on oocyte maturation that is doses dependent. With increasing concentration of the extract, the rate of maturation immature oocytes increased. تفاصيل المقالة