Technical Abstract: This study describes the mapping of 42 bovine gene-associated markers to the cattle genome using expressed sequence tag (EST) data derived from the mammary gland. A total of 21 gene loci were placed on the USDA reference linkage map, and 36 were positioned on the Roslin 3000-rad radiation hybrid (RH) map using these markers. Combined, 15 genes were positioned on both maps. Although no novel regions of conserved synteny between the cattle and human genomes were identified, the map coverage between genomes was increased as defined regions of conserved synteny were extended for bovine chromosomes 8, 25 and 29. Overall, these data improve the resolution of the human-bovine comparative maps and will assist future efforts to integrate bovine RH and linkage map data. Accession Nos. BV005755 through BV005814.