Alcohol dehydrogenase II (ADH II, structural gene alcB) was purified from a strain H1035, biA1; alcE1; alc500 alcD1, which produces 100-times more ADH II activity than the alcAalcR deletion strain (alc500). Antibodies were raised against this ADH, and were used to screen a cDNA library in lambda gt11. We have isolated the gene for an ADH which is over-expressed in H1035, and which we believe to be the alcB gene: cDNA and genomic clones were sequenced. The sequence contains three introns and encodes a protein of 367 amino acids. This protein shows a clear level of identity to a range of alcohol dehydrogenases, but is no more closely related to the ADH I and ADH III previously described in A. nidulans than to the ADHs of S. pombe and S. cerevisiae. The significance of consensus sequences found in the 5' region of the gene is discussed in relation to the regulation of the gene.