β-N-Acetylhexosaminidase (EC 3.2.1.52) was purified from the culture filtrate of Pycnoporus cinnabarinus to homogeneity by polyacrylamide disc gel electrophoresis. The ratio of β-GlcNAcase activity to β-GalNAcase activity remained constant during the purification process. The molecular weight of this enzyme was estimated to be about 120,000 by gel filtration, and the isoelectric point was at about pH 5.4. The optimum pH was at 2.2 for pNPGlcNAc and around 3.7 for pNPGalNAc. The enzyme was relatively stable at acid pH range of 2~4 (for 45 hr at 5°C) and below 45°C (for 10 min at pH 2.8). The enzyme hydrolysed chito-oligosaccharides, such as N,N-diacetylchitobiose, N,N,N-triacetylchitotriose and N,N,N,N-tetraacetylchitotetraose.