Two polygalacturonases (poly-α-1,4-galacturonide glycanohydrolase, EC 3.2.1.15) from the culture fluids of Verticillium albo-atrum were purified and characterized. Gel permeation and exchange chromatography followed by double isoelectric focusing have been used to separate and purify an exopolygalacturonase and an endopolygalacturonase. The exopolygalacturonase had a molecular weight of 44 000, pI of 6.5, and pH optima of 4.5 for pectin and 5.25 for sodium polypectate. The endopolygalacturonase had a molecular weight of 34 500, pI of 9.7, and pH optima of 5.0 for pectin and 6.0 for sodium polypectate. Both purified enzymes were electrophoretically homogeneous on polyacrylamide gels and exceptionally stable when stored in solution at 4°. The endo-enzyme was 20 times as effective in macerating plant tissue as the exo-enzyme.