Aldehyde dehydrogenase (ALDH) genes have been identified in almost all organisms from prokaryotes to eukaryotes, but particularly in plants knowledge is very limited with respect to their function. The data presented here are a contribution towards a functional analysis of selected Arabidopsis ALDH genes by using expression profiles in wild types and mutants. The Arabidopsis thaliana genome contains 14 genes which represent 9 families. To gain insight into the possible roles of aldehyde dehydrogenases from Arabidopsis, the expression patterns of five selected ALDH genes were analyzed under defined physiological conditions. Three genes (ALDH3I1, 3H1 and ALDH7B4) that belong to two different families are differentially activated by dehydration, high salinity and ABA in a tissue-specific manner. The other two genes (ALDH3F1 and ALDH22A1) are constitutively expressed at a low level. Transcript analysis of ALDH3I1 and ALDH7B4 in Arabidopsis mutants suggests that stress responses are differentially controlled by the phytohormone ABA as well as by pathways that affect sugar metabolism and fatty acid composition of membrane lipids. Our results indicate that the stress-associated ALDH genes participate in several pathways and that their regulation involves diverged signal transduction pathways.