Homogeneous endo-polygalacturonases (PGs) fromAspergillus nigerandFusarium moniliformewere used to prepare rabbit antisera. IgG were purified from antisera by Protein A-sepharose chromatography. Purified IgG were tested against endopolygalacturonases fromSclerotium rolfsii, Sclerotinia sclerotiorum, Rhizoctonia solani, Rhizoctonia fragariaeandFusarium oxysporum. Double immunodiffusion tests, ELISA tests and Western blottings showed that all the enzymes react with both antisera suggesting that a basic PG structure is mantained among the different fungi.