We report putative quantitative trait loci affecting female fertility and milkproduction traits using the merged data from two research groups that conductedindependent genome scans in Dairy Bull DNA Repository grandsire families toidentify quantitative trait loci (QTL) affecting economically important traits.Six families used by both groups had been genotyped for 367 microsatellitemarkers covering 2713.5 cM of the cattle genome (90%), with an average spacingof 7.4 cM. Phenotypic traits included PTA for pregnancy rate and daughterdeviations for milk, protein and fat yields, protein and fat percentages,somatic cell score, and productive life. Analysis of the merged datasetidentified putative quantitative trait loci that were not detected in theseparate studies, and the pregnancy rate PTA estimates that recently becameavailable allowed detection of pregnancy rate QTL for the first time. Sixty-oneputative significant marker effects were identified within families, and 13 wereidentified across families. Highly significant effects were found on chromosome3 affecting fat percentage and protein yield, on chromosome 6 affecting proteinand fat percentages, on chromosome 14 affecting fat percentage, on chromosome 18affecting pregnancy rate, and on chromosome 20 affecting protein percentage.Within-family analysis detected putative QTL associated with pregnancy rate onsix chromosomes, with the effect on chromosome 18 being the most significantstatistically. These findings may help identify the most useful markersavailable for QTL detection and, eventually, for marker-assisted selection forimprovement of these economically important traits.