Background and Objectives:Studies have shown that fatty acids affect maturation of oocytes, however, studies carried out on the effect of omega-3 on in vitro maturation of oocytes, are limited. The aim of this research was to investigate the effects of omega-3 on in vitro maturation of oocytes of mouse at the stage of germinal vesicle. Methods:In this in vitro experimental study, NMRI mice aged 6 to 8 weeks, were super ovulated and killed 44 hours later, then their ovaries were removed, and immature oocytes were used for in vitro maturation. Immature oocytes were treated with omega-3 at doses of 10 and 100 µM, after 24 hours, the maturation of the oocytes was examined by invert microscope. The data were analyzed using chi square test.Results: Exposure of immature oocytes to 10 and 100 µM of omega-3 resulted in increased rate of mature oocytes compared to the control group (p<0.05 and p<0.01, respectively). Maturation rate was also higher in the group exposed to lower dose of omega-3 (10 µM) compared to the group exposed to higher dose (100 µM) of omega-3 (p<0.01). Conclusion: Addition of low doses of omega-3 to oocyte maturation medium, significantly increase the maturation rate of immature oocytes.