Liquid membrane reactors are well known for metal extraction. This technology may also be applied to the immobilization of enzymes in enzyme emulsions. The use of liquid membrane reactors for enzymatic bioconversions has several advantages in comparison to solid membrane reactors and conventional immobilization techniques: there is no membrane fouling, enzyme emulsions can be used in cell-free fermentation broths, in complex mixtures the membrane can preselect the desired substrate for enzymatic reaction, and substances that might decrease the enzyme activity can be excluded. The separation effect is not based on differences in molecular weight but on the chemical behavior of the substances to be separated. Thus, it is not necessary to use cofactors with increased molecular weight for enzymatic reactions, since the coenzyme cannot permeate the liquid membrane. The three systems presented here indicate that enzyme systems can be easily immobilized in liquid surfactant membrane emulsions and there is a broad field of application for enzyme emulsions.