The cryophilic wine yeasts Saccharomyces bayanus YM-84 and YM-126 were used for hybridization with the mesophilic wine yeast Saccharomyces cerevisiae OC-2. All six hybrids were stable in tetrad analysis and pulsed field gel electrophoresis, even after twenty subcultures over two years. The fermentabilities of these hybrids at a low temperature of 7 degrees C were superior to the mesophilic wine yeast and the same as the cryophilic wine yeasts. Conversely, their fermentabilities at the intermediate temperatures of 28 and 35 degrees C were similar to the mesophilic wine yeast. For laboratory-scale wine-making using Koshu grape juice at 10 degrees C, the fermentability of these hybrids was superior to the mesophilic wine yeast. They also produced higher amounts of malic acid and flavor compounds such as higher alcohols, beta-phenylethyl alcohol, isoamyl acetate and beta-phenylethyl acetate, and lower amounts of acetic acid than those of OC-2. These results suggest that the cryophilic wine yeast S. bayanus is useful for improving the low temperature fermentation ability of wine yeast strains.