Using the protoplasts fusion technique, two Sacch.ca rlsbergenssP-1001 and P-1015 which are physiologically and biochemically different were successfully fused .Thirteen fusants were obtained which had been identifild by the variety of nutritional requirement, mating type, DNA contents and cell volume Immunochemical identification had obtained same result. This result indicated that the yeasts with immunochemical markers can be practically emplyed for yeast protoplast fusion breeding.