The recessive spontaneous sy18 mutation with nonhomologous synapsis was mapped in rye. The sy18 gene was located in the centromeric region of chromosome 2R in relation to three rye SSR (simple sequence repeats) loci, i.e., Xrems1130, Xrems1203, and Xscm43, and one wheat SSR locus Xgwm132. The desynaptic sy18 gene is located in the interval between Xrems1130 and Xrems1203 markers at a distance of 0.5cM and 3.1 cM, respectively. The possible evolutionary relationships of the mapped gene with homologous loci of the related species are discussed.