A chitin-degrading bacterial strain, KN1699, isolated from Yatsu dry beach (Narashino, Chiba Prefecture, Japan), was identified as ribrio parahaemolyticus. Treatment of powdered chitin with crude enzyme solution prepared from the supernatant of KN1699 cultures yielded a disaccharide, beta-D-N-acetylglucosaminyl-(1,4)-D-glucosamine (GlcNAc-GlcN), as the primary chitin degradation product. The extracellular enzymes involved in the production of this heterodisaccharide, chitinase (Pa-Chi; molecular mass, 92 kDa) and chitin oligosaccharide deacetylase (Pa-COD; molecular mass, 46 kDa), were isolated from the crude enzyme solution, and their hydrolysis specificities were elucidated. These studies confirmed that (1) Pa-Chi hydrolyzes chitin to produce (GlcNAc)(2) and (2) Pa-COD hydrolyzes the acetamide group of reducing end GlcNAc residue of (GlcNAc)(2). These findings indicate that GlcNAc-GlcN is produced from chitin by the cooperative hydrolytic reactions of both Pa-Chi and Pa-COD.