Four strains of microorganisms which have activity of chloroacetophenone reduction were screened, in which Saccharomyces cerevisiae B5 showed the highest activity and good stereoselectivity. This strains showed different activity on the reduction of various substrates in the following order: 2'-chloroacetophenone > 2-chloromethylacetophenone > 4'-chloroacetophenone > 3'-chloroacetophenone > acetophenone. Ethanol is the best cosubstrate and its optimal concentration is 5%.