Obesity, the leading metabolic disease in the world, is a serious health problem in industrialized countries. The Zizyphus jujuba fruit has been used as traditional Chinese medicinal herb and considered to affect various physiological functions in the body for thousands of years. We investigated the anti-obesity effect of Z. jujuba on adipocyte differentiation of 3T3-L1 preadipocytes and found that treatment with an extract of Z. jujuba suppressed lipid accumulation and glycerol-3-phosphate dehydrogenase (GPDH) activity without affecting cell viability. Further fractionation of the initial Z .jujuba extract with organic solvent revealed that the chloroform fraction (CHCl(3)-F) elicited the most inhibitory effect, which involved significant attenuation of the expression of key adipogenic transcription factors, including peroxisome proliferator-activated receptor (PPAR)gamma and CCAAT enhancer binding proteins (C/EBPs) at the protein level. These results suggest that CHCl(3)-F may block adipogenesis, at least in part, by decreasing the expression of PPARgamma, C/EBPalpha and beta.