In particular, eicosapentaenoic acid(EPA), a long-chain ω-3 fatty acid (PUFA), is anatural high-affinity ligand for PPARγ. Despite theincreasing clinical use, the mechanisms by whichEPA exerts its effects is yet relatively unknown.The aim of the present study was to investigate theeffects of EPA on gene expression levels of PPARγand CYP-19 in cultured GC from patients undergoingIVF, and also to compare these effects withthose in GC of PCOS patients. The gene discussed is CYP19A1; the disease is polycystic ovary syndrome.