In　aqueous　buffer　system　containing　surfactants　of　SDS,　CTAB　and　Emulsifier　OP-6,　the　asymmetric　reduction　of　2-octanone　to　(S)-2-octanol　with　Saccharomyces　cerevisiae　cells　was　studied.　The　results　indicated　that　the　yield　and　product　e.e.　were　disappointingly　low　due　to　the　serious　reverse　reaction　and　side　reaction　in　the　surfactant-free　system.　Particularly,　at　the　substrate　concentration　of　10　mmol/L,　they　were　77.4%　and　78.8%　for　96　h　reaction.　With　addition　of　surfactants　to　the　system,　the　rates　of　reverse　and　side　reactions　were　decreased　by　Emulsifier　OP-6　and　CTAB,　with　the　effective　increase　of　the　average　positive　reaction　rate.　In　the　systems　containing　0.4　mmol/L　Emulsifier　OP-6　or　0.04　mmol/L　CTAB,　the　yield　and　e.e.　value　were　88.4%,　91.1%　and　97.0%,　94.5%),　respectively,　obviously　higher　than　those　in　the　reaction　system　without　surfactant.　The　further　work　showed　that　the　enhancement　of　efficiency　and　enantioselectivity　of　the　asymmetric　reduction　resulted　from　the　effect　of　the　surfactants　on　the　cell　characteristics　such　as　growth,　membrane　penetrability,　etc.　Among　the　surfactants　investigated,　Emulsifier　OP-6　performed　best.