Enzymes are catalytically active not only in aqueous solution but also in organic media (low-water solvent system, reversed micelles, monophasic cosolvent system, and biphasic organic/aqueous system). Of special interest is the low-water solvent system, because it is important to organic synthesis. In this review,attention is focused on the factors that influence enzyme catalysis in a low-water solvent including the role of water, selection of the solvent and support, some special proterties acquired by enzymes in such a system are discussed. Examples of applications with the use of enzymes in organic synthesis,analysis, and polymer chemistry,are listed.