Multicolour genomic in situ hybridization was carried out in wheat-rye hybrids and in a wheat-rye translocation line. Different hybridization conditions and mixture compositions were used, and A, B and D genomes of hexaploid wheat as well as the R genome of rye were distinguished simultaneously in somatic cells. Combination of genomic and rDNA probes in multicolour in situ hybridization was also performed to identify chromosomes within a specific genome.