We have discovered new characteristics of D-erythrulose reductase, namely, that it can catalyze reduction of not only D-erythrulose but also such diketones as diacetyl, These substrates have a common structure with two neighboring carbonyls possibly in s-cis plane structure, showing that the enzyme may rigorously distinguish between substrates and other compounds. D-Erythrulose reductase was predominantly located in the kidney and the liver of the chicken. The obtained results suggest that D-erythrulose reductase plays an important role in metabolizing alpha-dicarbonyls in animal organs, because these diketones widely occur in natural foods.