The hisH gene of Corynebacterium glutamicum encoding glutamine amidotransferase has been isolated by complementation of his auxotrophic mutant of Escherichia coli, using a C. glutamicum genomic DNA library. Cloned DNA fragments containing hisH gene can also complement hisA, hisF, and hisI auxotrophs of E. coli, suggesting that these genes are clustered in the genome. We determined the nucleotide sequences of the minimal fragment containing the hisH gene region. The gene consists of 636 bp and codes for a polypeptide of 212 amino acids with a molecular mass of about 24 kDa, showing high level of identity with reported amino acid sequences of glutamine amidotransferase from other organisms.