Cinnamyl alcohol dehydrogenase (CAD) is an enzyme involved in lignin biosynthesis. We have previously isolated pure CAD enzyme from Norway spruce (Picea abies L.) cell culture. Here we report on partial protein sequences of the 42 kDa CAD polypeptide. A cDNA encoding CAD was isolated from the spruce cell culture. The open reading frame of a full-length cDNA coded for a 357 amino acid polypeptide with a calculated M(r) of 38,777 Da. The identity of the deduced polypeptide was verified by comparison with amino acid sequences of tryptic peptides from the purified enzyme. Southern blot analysis showed the presence of only one gene for CAD. Sequence comparison with CAD from tobacco and with a N-terminal protein sequence from loblolly pine CAD showed an identity of 69.7% and 91.5%, respectively. Treatment of spruce cell cultures with elicitor, as well as of seedlings with ozone both markedly increased the CAD mRNA level.