Genome scans can be employed to identify chromosomal regions and eventuallygenes (quantitative trait loci or QTL) that control quantitative traits ofeconomic importance. A three-generation resource family was developed by usingtwo Berkshire grand sires and nine Yorkshire grand dams to detect QTL for growthand body composition traits in pigs. A total of 525 F2 progeny were producedfrom 65 matings. All F2 animals were phenotyped for birth weight, 16-day weight,growth rate, carcass weight, carcass length, back fat thickness, and loin eyearea. Animals were genotyped for 125 microsatellite markers covering the genome.Least squares regression interval mapping was used for QTL detection. Allcarcass traits were adjusted for live weight at slaughter. A total of 16significant QTL, as determined by a permutation test, were detected at the 5%chromosome-wise level for growth traits on Chromosomes (Chrs) 1, 2, 3, 4, 6, 7,8, 9, 11, 13, 14, and X, of which two were significant at the 5% genome-wiselevel and two at the 1% genome-wise level (on Chrs 1, 2, and 4). For compositiontraits, 20 QTL were significant at the 5% chromosome-wise level (on Chrs 1, 4,5, 6, 7, 12, 13, 14, 18), of which one was significant at the 5% genome-wiselevel and three were significant at the 1% genome-wise level (on Chrs 1, 5, and7). For several QTL the favorable allele originated from the breed with thelower trait mean.