The nucleotide sequence of the G6-amylase gene from alkalophilic Bacillus sp. H-167 was determined. The open reading frame of the gene consisted of 2865 base pairs, encoding 955 amino acids. The NH2-terminal amino acid sequence analysis of the G6-amylase indicated that the enzyme had a single peptide of 33 amino acid residues and the mature enzyme was composed of 922 amino acids, giving a molecular mass of 102,598. Identity of the NH2-terminal amino acid sequences among each component of the multiform G6-amylase suggested the proteolytic processing of the COOH-terminal side of the enzyme. The DNA sequence and the deduced amino acid sequence of the G6-amylase gene showed no homology with those of other bacterial alpha-amylases although the consensus amino acid sequences of the active center were well conserved.