Two mutants, which were able to grow at 35°C and had high ethanol -resistance at 25°C with increased ethanol yield at the intermediate temperatures of 25 and 30°C, were isolated from the cryophilic wine yeast Saccharomyces bayanus YM-84 M (Arg^-), and their genetic properties were studied. Hybrids obtained from the mutants and the cryophilic wine yeast YM-84 A (His^-) were unable to grow at 35°C, and showed inferior abilities for ethanol-resistance and to produce ethanol at the intermediate temperatures. In tetrad analysis of the hybrids, the each property was segregated irregularly. Phenotypes of spore-clones isolated from the hybrids suggested that the properties of growth at 35°C and increased ethanol yield at 30°C were related to high ethanol-resistance. In the laboratory-scale wine-making using Koshu grape juice, the mutants showed good fermentability at a low temperature of 10°C and high ethanol yield at an intermediate temperature of 25°C.