A gene encoding chitinase II from Aeromonas sp. no. 10S-24 was cloned into Escherichia coil DH5 alpha by using pUC19 and its nucleotides were sequenced. The structural gene consisted of 1626 bp encoding 542 amino acid residues with a characteristic signal peptide. A typical promoter sequence and Shine-Dalgarno (SD) region were located upstream of the initiation ATG codon. The deduced amino acid sequence of the cloned chitinase II. showed sequence homology with chitinase from Saccharopolyspora erythraea (26%). The chitinase II had Pro-Thr- rich domains, consisting of repeat sequences of 47 amino acids, that are not conserved in other chitinases from bacteria. Generally, repeat sequences of amino acids rich in Pro and/or Thr appear to link discrete functional domains in many cellulases and xylanases.