Japanese plum (Prunus salicina Lindl.), a species of the Rosaceae family, carries the S-RNase-mediated gametophytic self-incompatibility system. Self-incompatibility is manifested if the S-haplotype of the pollen is carried also by the pollinated flower. Thus, for fertilization to occur, the cultivars have to be genetically compatible. The haplotype is conferred by an S-locus, which contains the style-specific expressed S-RNase and the pollen-specific expressed F-box genes (SFB). Since both the S-RNase and the SFB genes are multiallelic and are characteristic of each of the S-haplotypes, they are ideal markers for molecular S-typing. In this work, seven SFBs, from eight japanese plum cultivars, were cloned and sequenced. Five of the alleles were published recently and two SFBg and SFBk are new. The physical linkage of SFBb and SFBc to their adjacent S-RNase was determined; it is 544 base pairs (bp) and 404 bp for the Sb and Sc loci, respectively.