A Fusarium isolate produced polygalacturonase (PG) of the endo or I type. Pectic acid was hydrolyzed at random liberating intermediate oligogalacturonic acid residues which were separated chromatographically. The formation of PG in the presence of a specific carbon source was shown to be an induced synthesis. It was also shown that sucrose was inhibitory of production but not activity of PG. Culture techniques precluded mutation and selection as significant factors in the induced formation of PG. The similarity of induced enzyme synthesis in Fusarium and certain bacterial enzymes is discussed and the significance of the work as related to wilt mechanisms is considered.