Abstract: Haploid yeast cells mate to form a zygote, whose progeny are diploid cells. A fundamentally sexual event, related to fertilization, yeast mating nevertheless exhibits cytological properties that appear similar to somatic cell fusion. A large collection of mutations that lead to defects in various stages of mating, including cell fusion, has allowed a detailed dissection of the overall pathway. Recent advances in imaging methods, together with powerful methods of genetic analysis, make yeast mating a superb platform for investigation of cell fusion. An understanding of yeast cell fusion will provide insight into fundamental mechanisms of cell signaling, cell polarization, and membrane fusion.