A gene named phd1+ encoding a protein highly homologous to the yeast and human histone deacetylases, such as Saccharomyces cerevisiae Rpd3p and human HDAC1, was cloned from Schizosaccharomyces pombe. The immune complex isolated from S. pombe cells expressing Phd1 fused to the FLAG epitope showed histone deacetylase activity, which was inhibited by trichostatin A (TSA), a specific inhibitor of histone deacetylase. The null mutation of phd1+ resulted in a marked decrease in the total cellular histone deacetylase activity and an increase in the sensitivity to TSA. Although the phd1 disruptant showed no obvious defect in the mitotic cell cycle or mating, both homothallic haploid and heterothallic diploid cells failed to form spores in the absence of phd1+. These results indicate that phd1+ encodes a histone deacetylase, which is involved in the meiotic cell cycle in S. pombe.