The subunit composition of RNA polymerase II (polII) was compared between the budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe. For this purpose, we partially purified the enzyme from S. pombe. Judging from the co-elution profiles in column chromatographies of both the RNA polymerase activity and the two large subunit polypeptides (subunit 1 (prokaryotic beta' homologue) and subunit 2 (beta homologue)), the minimum number of S. pombe polII-associated polypeptides was estimated to be ten, less than the proposed subunit number of the S. cerevisiae enzyme. These ten putative subunits of S. pombe polII correspond to subunits 1, 2, 3, 5, 6, 7, 8, 10, 11 and 12 of the S. cerevisiae counterparts.