Zea mays (L.) histone deacetylase HD2 was identified as a new type of histone deacetylase (HDAC) unrelated to the well-known Rpd3p and Hda1p families but with sequence homology to peptidyl-prolyl els-trans isomerases (PPIases). Here we show that HD2 is a multigene family with highly related members in various plant species. Gene analysis revealed a similar exon/ intron structure in Arabidopsis thaliana (L.) Heynh. and Z. mays, and most of the sequences analyzed were demonstrated to possess an intron of the very rare AT-AC type.