Background CCAAT/enhancer-binding protein β(C/EBPβ) is required for mitotic clonal expansion (MCE) during adipogenesis. It is still unclear how C/EBPp regulates MCE in the earlier differentiation programs of 3T3-L1 preadipocytes. The purpose of this paper was to understand why C/EBPβ is required for preadipocyte proliferation, and identify new target genes of C/EBPP with chromatin immunoprecipitation (ChlP)-on-chip. Methods Postconfluent growth-arrested 3T3-L1 preadipocytes were induced to differentiation using a standard differentiation protocol. Chip was performed at 20 hours after induction with specific anti-C/EBPβ antibodies. The precipitated DNA was amplified, labeled and hybridized with a mouse promoter microarray. Compared with the control in which the ChIP experiment was performed with non-specific antibody, only the genes with a signal increasing more than 2 fold were considered as candidate genes.Results A total of 110 candidate genes were identified. BTG3 associated nuclear protein (SMAR1, Banp) and tripartite motif-containing 35 (Hls5, trim35) were two target genes among the 110 candidate genes which are involved in cell cycle regulation; the binding of C/EBP3 to the promoter of banp and trim35 was verified by ChlP-PCR. Conclusion C/EBPβ may regulate preadipocyte proliferation through activation of banp and trim35.