A unique resource population was produced to facilitate detection ofmicrosatellite markers associated with quantitative trait loci controllingantibody (Ab) response in broiler chickens. Three F1 males were produced bymating two lines divergently selected on Ab response to Escherichia colivaccination. Each F1 male was mated with females from four genetic backgrounds:F1, high-Ab line (HH), low-Ab line and commercial line, producing three resourcefamilies, each with four progeny types. About 1700 chicks were immunized with E.coli and Salmonella enteritidis vaccines. Selective genotyping was conducted onthe individuals with highest or lowest average Ab to E. coli and S. enteritidiswithin each progeny type in each sire family. Twelve markers were significantlyassociated with Ab to E. coli and six of them were also associated with Ab to S.enteritidis, mostly exhibiting a similar low effect (approximately 0.35phenotypic SD) in all progeny types. Four markers exhibited a highly significantand much larger effect (approximately 1.7 SD), but only in progeny of femalesfrom the HH, suggesting that a backcross to the high parental line should bepreferred over the commonly used F2 population. Results from two markerssuggested a quantitative trait locus on chromosome 2 around 400 cM. The markerMCW0083, significant in two sire families, is closely linked to the bonemorphogenetic protein 2 (BMP2) gene, known to be associated with the control ofT-cell transformation in humans.