A conserved region of a polygalacturonase (PG) gene from Penicillium griseoroseum was PCR amplified and used to screen a genomic library from this fungus. The nucleotide sequence of the isolated clone (pggI) consisted of 1497 bp, including a coding region of 1251 bp. This region potentially encodes a protein of 376 amino acids, and is interrupted by two introns. Extensive homology was observed between this protein and several fungal endopolygalacturonases. DNA hybridization analyses revealed that there is a low copy number of pggI in the P. griseoroseum genome, probably one or two copies.