N-Formyl-L-aspartyl-L-phenylalanine methyl ester (N-formyl aspartame, F-AspPheOMe) was synthesized enzymatically utilizing an extractive reaction in an aqueous/organic biphasic system. The N-formyl aspartame yield in a pure aqueous monophasic system was, in general, ca. 3%, however, it was over 80% in a water/1-butanol biphasic system using a simultaneously extractive operation of an enzymatic reaction in an aqueous phase and a product separation from an aqueous to an organic phases.