Twenty-three kinds of commercially available enzymes were subjected to the screening test for xylanolytic activities, namely, endo-β-xylanase, β-xylosidase, α-arabinofuranosidase and α-glucuronidase.The majority of the enzymes contained some of the activities. The above enzymes were also submitted to the hydrolyzable test on the arabinoglucuronoxylan of corn hull. Among them, Cellulase C-0901 (Sigma Chemicals) originating from Penicillium funiculosum, although lacking in a-glucuronidase, degraded the xylan very well, and released 80.5% of arabinose and 60.8% of xylose based on the component sugars of the xylan. On the other hand, Cellulase 'Onozuka' R-10 (Yakult Co.) originating from Trichoderma viride, although containing all of the xylanolytic activities, decomposed hardly any of the arabinoglucuronoxylan. According to these results, commer cially available enzymes contained high and various xylanolytic activities. However, the intensities of enzyme activity and hydrolyzable ability differed remarkably in the degradation of arabinogluc uronoxylan. In addition, Cellulase C-0901 was most suitable among them for the enzymatic hydrolysis of the xylan.