A cDNA library containing a chitin deacetylase (CDA) gene from a zygomycete Gongronella butteri was constructed and the complete gene was sequenced. The complete gene contains an open reading frame of 1290 nucleotides which encodes a sequence of 430 amino acid residues. The gene sequence consists of nucleotides encoding a polysaccharide deacetylase domain located in the middle, covering 34% of the entire sequence. This domain shares high sequence similarities with CDAs of fungi and other deacetylases including the nodb-like protein from Sinorhizobium meliloti and Bacillus subtilis, xylanase D from Cellulomonas fimi, and acetylxylan esterase A from Streptomyces lividans. The deduced amino acid sequence shows homology with CDAs from Mucor rouxii (48% identity) and Phycomyces blakesteeanus (30% identity). Phylogenetic analysis reveals that CDAs are clustered in accordance with the taxonomic classification of the fungi.