Jun dimerization protein 2 (JDP2) is a novel member of AP-1 family and acts as a general repressor of a variety of transcription. JDP2 is able to bind to specific sites in target gene such as c-jun by forming homodimer or heterodimers with a Jun/ATF family member to counteract their transcriptional activity. Previously we showed that JDP2 inhibits the retinoic acid (RA) dependent transcription by recruiting a histone deacetylase 3 (HDAC3) complex to the promoter region of the target genes. We present here that JDP2 has an inhibitory activity of acetylation of all core histones mediated by histone acetyltransferase (HAT) both of p300 and PCAF in vitro. The studies of both histone-binding and HAT-inhibitory activity using a variety of recombinant JDP2(s) indicated that JDP2 might target histone itself through the histone-binding domain of JDP2, which is essential but not sufficient for the inhibition of acetylation. Therefore, our data suggested that HAT-inhibitory activity of JDP2 could in part explain the transcriptional repression of several target genes.