Sweet cherries are generally self-incompatible, caused by a gametophytic self-incompatibility system. Two genetic factors (S-alleles) determine the fertility of sweet cherry genotypes. Dependent on the S-allele constitution of the cultivars, cross-incompatibility groups of sweet cherry cultivars exist. The knowledge about the S-allele combinations of the cultivars is very important for the fruit growers and breeders. In the last years molecular methods have been developed to distinguish the S-alleles in sweet cherries. An update of the S-genotype of 734 sweet cherries was summarized. The data includes results of 51 new varieties supplemented with data from various published sources and personal information up to 2012. A total of 18 S-alleles were detected in 47 incompatibility groups in sweet cherry.