By use of the polymerase chain reaction and synthetic oligonucleotides designed from conserved regions, we amplified a fragment of a gene from Ustilago maydis encoding a putative histone deacetylase. With this probe we isolated the full gene from a minigenomic library. The gene (designated as Umhda2) contains an open reading frame (ORF) of 1701bp encoding a protein of 566 amino acids. Multiple comparison analysis with other histone deacetylases suggests that the Umhda2 gene product belongs to the Rpd3-related family of proteins. The highest degree of homology with histone deacetylases from other organisms corresponded to Hdalp of Schizosaccharomyces pombe and Rpd3p of Saccharomyces cerevisiae with 64.2 and 62.2% of sequence similarity, respectively. It displayed a substantially lower similarity with another histone deacetylase from U. maydis (Hdalp, 52.4%). Semi-quantitative RTPCR results indicate that the gene is transcriptionally up-regulated during the in vitro yeast-to-mycelium dimorphic transition.