We have isolated and sequenced a partial tomato alcohol dehydrogenase (Adh) cDNA clone. Expression of tomato Adh was studied at the messenger RNA level in seedlings, roots, and fruit. High induction was observed under hypoxic conditions, both in tomato seedlings and in roots. In addition, the Adh mRNA was present at the mature green and pink stage of the tomato fruit, and was highly induced in late ripening. Moreover, an artificial ripening treatment resulted in at least 50-fold induction compared to the mature green mRNA level. Genomic DNA gel blotting suggested the presence of a multigene family for Adh in tomato.