The genomic DNA encoding a polygalacturonase (PG) from the filamentous fungus Penicillium janthinellum was cloned by genome walking using single specific primer-polymerase chain reaction (SSP-PCR), and the complete nucleotide sequence was identified. The PG gene consists of 1266-bp encoding a protein of 371 amino acids, interrupted by two introns of 88 and 62-bp in length. Comparison of the amino acid sequences revealed the presence of a high degree of homology among PGs from different fungi. When the P. janthinellum PG gene was introducted into Aspergillus oryzae, the transformants showed about three-fold enhanced PG activity relative to the recipient parent strain, indicating that the gene encoded in the cloned DNA fragment was the fuctional PG gene.