Ovulation rate is an integral component of litter size in swine, but isdifficult to directly select for in commercial swine production. Because a QTLhas been detected for ovulation rate at the terminal end of chromosome 8p,genetic markers for this QTL would enable direct selection for ovulation rate inboth males and females. Eleven genes from human chromosome 4p16-p15, as well asone physiological candidate gene, were genetically mapped in the pig. Largeinsert swine genomic libraries were screened, clones were isolated and thenscreened for microsatellite repeats, and informative microsatellite markers weredeveloped for seven genes (GNRHR, IDUA, MAN2B2, MSX1, PDE6B, PPP2R2C, andRGS12). Three genes (LRPAP1, GPRK2L, and FLJ20425) were mapped using genotypingassays developed from single nucleotide polymorphisms. Two genes were assignedsince they were present in clones that contained mapped markers (HGFAC andHMX1). The resulting linkage map of pig chromosome 8 contains markers associatedwith 14 genes in the first 27 cM. One inversion spanning at least 3 Mb in thehuman genome was detected; all other differences could be explained byresolution of mapping techniques used. Fourteen of the most informativemicrosatellite markers in the first 27 cM of the map were genotyped across theentire MARC swine resource population, increasing the number of markers typedfrom 2 to 14 and more than doubling the number ofgenotyped animals withovulation rate data (295 to 600). Results from the revised data set for the QTLanalysis, assuming breed specific QTL alleles, indicated that the most likelyposition of the QTL resided at 4.85 cM on the new linkage map (F1,592 = 20.5150,genome-wide probability less than 0.015). The updated estimate of the effect ofan allele substitution was -1.65 ova for the Meishan allele. The F-ratio peakwas closest to markers for MAN2B2 (4.80 cM) and was flanked on the other side bymarkers for PPP2R2C. Two positional candidate genes included in this study areMAN2B2 and RGS12. These results validate the presence of a QTL affectingovulation rate on chromosome 8 and facilitate selection of positional candidategenes to be evaluated.