Abstract: A process for the production of a 4-halo-3-hydroxybutyronitrile which comprises reacting an epihalohydrin with a halohydrin-halide-lyase originating from a microorganism selected from the group consisting of: Corynebacterium sp. N-2354 FERM BP-2726 and Microbacterium sp. N-4701 FERM BP-2644 in the presence of an alkali cyanide to thereby convert the epihalohydrin into the 4-halo-3-hydroxybutyronitrile and collecting the product thus formed is disclosed. According to this process, a 4-halo-3-hydroxybutyronitrile which is highly useful in the syntheses of various medicines and physiologically active substances can be easily and efficiently produced from an inexpensive starting material.