A full length ovine steroid 11β-hydroxylase (cytochrome P-450 1 1 β ) cDNA clone from a sheep adrenal cortex cDNA library was isolated. Sequence analysis indicates that this cDNA clone resembles bovine P-450 1 1 β cDNA (95% nucleotide sequence homology) more closely than rat P-450 1 1 β cDNA (69% nucleotide sequence homology). Although the levels of nucleotide sequence homology of this cDNA clone to the rat P-450 1 1 β cDNA and the rat P-450 a l d o cDNA are similar, the putative amino acid sequence shows a closer resemblance to rat P-450 a l d o protein. Northern blot analysis shows that there are three sizes of transcript and they are expressed throughout the adrenal cortex.