AbstractABSTRACT Matings between (C57BL/6 × DDK)F1 females and C57BL/6 males result in a significant excess of offspring inheriting maternal DDK alleles in the central region of mouse chromosome 11 due to meiotic drive at the second meiotic division. We have shown previously that the locus subject to selection is in the vicinity of D11Mit66, a marker closely linked to the Om locus that controls the preimplantation embryolethal phenotype known as the “DDK syndrome.” We have also shown that observation of meiotic drive in this system depends upon the genotype of the sire. Here we show that females that are heterozygous at Om retain the meiotic drive phenotype and define a 0.32-cM candidate interval for the Responder locus in this drive system. In addition, analysis of the inheritance of alleles at Om among the offspring of F1 intercrosses indicates that the effect of the sire is determined by the sperm genotype at Om or a locus linked to Om.