We have cloned rpbA encoding the RNA polymerase II largest subunit (polIIL) from a filamentous fungus, Aspergillus oryzae. The rpbA product included eight highly conserved regions and the carboxyl-terminal domain (CTD). A. oryzae polIIL CTD with 184 amino acids was composed of 25 CTD consensus repeats, which was a similar number to those of lower eukaryotes. The amino acids in each repeat of A. oryzae polIIL, however, conformed less to the CTD consensus than those of polIILs from other lower eukaryotes.