A multiallelic dinucleotide repeat (CA-microsatellite) polymorphism in bovine genomic DNA, designated RM004, was detected by PCR.Five alleles were detected in 26 parents from the international cattle reference families (CSIRO, ILRAD, Texas A&M).Codominant inheritance of the 5 alleles was demonstrated in 13 informative cattle reference families with a total of 180 offspring.The RM004 locus was mapped to chromosome 15.The RM004 locus was amplified successfully in 11 unrelated sheep.Five alleles were detected, with sizes of 167, 169, 171, 173, and 177 bp.In 9 unrelated goats, 4 alleles were observed with sizes of 112, 114, 116, and 118 bp.