Barley (Hordeum vulgare) seedlings were exposed to flooding and activities of alcohol dehydrogenase (ADH) and their isoform profiles were determined. The flooding increased ADH activities in shoots and roots of the seedlings. By day 3, the activity increased to 4 and 3 times that of the initial level for the shoots and the roots, respectively. Only two bands of ADH isoform were found in the shoots and the roots of non-induced seedling, whereas five bands were identified in those of induced seedlings.