Sexual agglutination and pheromone interaction between cells of two mating types, a and α, in the yeast Saccharomyces globosus were studied.S. globosus was shown to produce mating-type-specific factors analogs to a- and α-mating pheromones of Saccharomyces cerevisiae and to undergo the sexual agglutination reaction between cells of two mating types.While the sexual agglutination of cells of different species was not observed, mating type a cells of each species were shown to respond to α-factors produced by the other species.Thus, the mating response of S. globosus was shown to be identical to what has been observed in two other species of the same genera: S. cerevisiae and Saccharomyces kluyveri.