Fusarium oxysporum, a soilborne phytopathogenic fungus, produces endo polygalacturonase (PG) which has been suggested to be related to disease development. A polyclonal antibody (PAb) APG1 was prepared against purified PG from F. oxysporum f. sp. lycopersici race 2. By direct tissue-blotted immunobinding assay (DT-IBA) with the antibody, PG production by the pathogen in the stem of the host plant was confirmed. Degenerate primers were designed based on partial amino acid residue information for the PG protein from the fungus: part of the PG-encoding gene was obtained by PCR. Using TAIL-PCR, the complete gene encoding PG was cloned and sequenced. The structural gene comprises 1318 bp coding for 371 amino acids with a putative signal peptide of 22 amino acids, and the open reading frame is interrupted by four introns of 47, 51, 50, and 54bp. The deduced amino acid sequence of the mature protein showed 82.9, 29.0, 27.6, 14.2, and 26.9% homology with those of F. moniliforme PG, Cochliobolus carbonum PGNI, Aspergillus niger PG, A. oryzae PG, and Sclerotinia sclerotiorum PGI, respectively.