This research was conducted in order to determine the effects of omega-3 on oocyte in vitro maturation and the level of expression of tribbles (TRIB1, TRIB2 and TRIB3 genes) in cumulus cells. Eight-ten weeks old NMRI mice were super-ovulated using 7.5 IU pregnant mare’s serum gonadotropin (PMSG, Intraperitoneal) and they were killed after 44 hours and their ovaries were removed. The oocytes were used for <em>in vitro</em> maturation and the cumulus-oocyte complexes (COCs) were released. Cumulus cells and oocytes were assigned into control, ethanol-treated and groups exposed to 10 and 100 μg/ml of omega-3. The cells were prepared to assess the maturation stage in order to evaluate the gene expression level. The data were statistically analyzed. Exposing oocytes to low dose (10 μg/ml) and high dose (100 μg/ml) of omega-3 resulted in a reduced rate of GV-stage oocytes, decreased MI-oocytes and increased MII-oocytes. The enhanced maturity of COCs was also detected in response to a high dose of omega-3 (100 μg/ml). Exposure of cumulus cells to omega-3 (10 and 100 μg/ml) induced TRIB2 and inhibited TRIB3 gene expression level; however, TRIB1 gene expression level increased and decreased in response to low (10 μg/ml) and high (100 μg/ml) concentrations of omega-3, respectively. The addition of omega-3 to the environment of oocytes or cumulus cells affected the maturation of oocytes and cumulus cells, which was followed by the differential expression of TRIB genes, suggesting that there was a role of fatty acid metabolism in the differentiation and maturation of cumulus cells.