The enhancing effects of yeasts on the viability of lactic acid bacteria (LAB) under acidic conditions were investigated.  Meyerozyma guilliermondii , coaggregative with both LAB strains under acidic conditions, significantly enhanced the viability of  Lactobacillus pentosus  and  L. paracasei  in pH 3.0 lactic acid (LA) buffer at 10°C (p < 0.05). Non-coaggregative yeasts ( Saccharomyces cerevisiae, Schizosaccharomyces pombe , and  Cyberlindnera saturnus ) also significantly enhanced the LAB viability (p < 0.05), and physical contact between LAB and yeasts was not essential for the viability-enhancing effect, indicating that the coaggregation had no relation to the enhancing mechanism. Although yeast metabolites and LA assimilation had no enhancing effect, hydrogen peroxide (H 2 O 2 ) decreased after yeast coincubation, and H 2 O 2  elimination improved  L. pentosus  viability. H 2 O 2  elimination alone did not sufficiently improve  L. paracasei  viability, but the addition of antioxidants was effective. These results suggest that the antioxidant activity of yeast increased the LAB viability under acidic conditions.