Sulfuretin is a natural flavonoid found in the plant Rhus verniciflua STOKES. The plant has been traditionally used as medicinal agent for antiviral, cathartic, diaphoretic, anti-rheumatic and sedative activities in East Asia. In this study we isolated and identified sulfuretin from R. verniciflua and investigated its anti-adipogenic activity against 3T3-L1 preadipocytes cells. We evaluated the effects of sulfuretin on the adipogenic transcription factors like peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), fatty acid synthase (FAS), Fabp4, adiponectin and zinc fingerprint protein (Zfp) 521 by gene expression (real-time QPCR) and Western blot analysis. Sulfuretin treatment at Day 0 and 2 showed significant reduction of lipid production in 3T3-L1 cells in concentration dependent manner. Gene expression analysis (real-time PCR) revealed that sulfuretin inhibited the both major adipogenic factors (C/EBPα, C/EBPβ and PPARγ) and minor adipogenic factors (sterol regulatory element-binding protein (SREBP1c), adiponectin, FAS, Fabp4, Zfp423, and Ebf1). Western blot analysis showed the increased expression of β-catenin and suppression of PPARγ after sulfuretin treatment. Overall, sulfuretin is a natural flavonoid having potent anti-adipogenic activity through the suppression of major adipogenic factors C/EBPα, C/EBPβ and PPARγ, which initiate adipogenesis.