Mevaldate reductase was purified 70-fold from rat liver. The partly purified enzyme had a molecular weight of 27000-30000, reduced certain aromatic aldehydes and was inhibited by barbiturates. These properties are similar to those of other animal tissue aldehyde reductases (EC 1.1.1.2) and it is suggested that mevaldate reductase be reclassified as one of this group.