The aim of this study was to examine the anti-adipogenic effect of germinated brown rice methanol extract (GBR) in 3T3-L1 adipocytes. The GBR inhibited adipocyte differentiation was measured by Oil Red O staining and glycerol-3-phosphate dehydrogenase (GPDH) activity in a dose-dependent manner without initiating any cytotoxicity. The mRNA levels of adipogenic transcription factors such as CCAAT/enhancer binding protein (C/EBPα), proliferator-activated receptorγ (PPARγ), and sterol regulatory element-binding protein-1c (SREBP-1c), and adipogenic genes, such as fatty acid synthase (FAS), adipocyte fatty acid-binding protein (aP2), and lipoprotein lipase (LPL), were significantly down-regulated by treatment with GBR when compared to that of untreated control cells. Moreover, tumor necrosis factor-α (TNF-α) and interlukin-6 (IL-6) mRNA expressions were attenuated by GBR in mature adipocytes. These data suggest that GBR exhibits an anti-adipogenic effect through the suppression of adipogenesis in 3T3-L1 adipocytes.