When Corticium rolfsii is grown under aerobic conditions in a medium containing one of several simple sugars or polysaccharides, it release α-L-arabinofuranosidase into the culture fluid. Araban and bran extract were found to be the most effective carbon sources in stimulating the production of the enzyme. Pectin and arabinose stimulated the production of the enzyme to a lesser degree, whereas xylose, glucose, galactose, and sucrose caused the formation of a relatively small amount of α-L-arabinofuranosidase. α-L-Arabinofuranosidase was demonstrated by its ability to hydrolyze phenyl-α-L-arabinofuranoside, araban, and arabinoxylan. The pH optimum of the enzyme was 2.5. At pH values of 2 to 9, the enzyme lost less than 15% of its activity during a 72-hr period at 2 C. At 70 C, its stability was greatest at pH values of 4 to 6.