The effect of change in unsaturated fatty acid composition on ethanol tolerance in Saccharomyces cerevisiae overexpressing ScOLE1 (a dagger 9 fatty acid desaturase gene of S. cerevisiae), CaFAD2 (a dagger 12 fatty acid desaturase gene of Candida albicans), or CaFAD3 (omega 3 fatty acid desaturase gene of C. albicans) was examined. ScOLE1 over-expression increased the total unsaturated fatty acid content and enhanced ethanol tolerance, compared with a control strain. In contrast, overexpression of CaFAD2 and CaFAD3, which led to production of linoleic acid (18:2) and alpha-linolenic acid (18:3), respectively, neither changed total unsaturated fatty acids nor enhanced ethanol tolerance. The total unsaturated fatty acid content rather than the degree of unsaturation is thus an important factor for ethanol tolerance.