Quantitative trait loci (QTL) for abdominal fatness and breast muscle weightwere investigated in a three-generation design performed by inter-crossing twoexperimental meat-type chicken lines that were divergently selected on abdominalfatness. A total of 585 F2 male offspring from 5 F1 sires and 38 F1 dams wererecorded at 8 weeks of age for live body, abdominal fat and breast muscleweights. One hundred-twenty nine microsatellite markers, evenly locatedthroughout the genome and heterozygous for most of the F1 sires, were used forgenotyping the F2 birds. In each sire family, those offspring exhibiting themost extreme values for each trait were genotyped. Multipoint QTL analyses usingmaximum likelihood methods were performed for abdominal fat and breast muscleweights, which were corrected for the effects of 8-week body weight, dam andhatching group. Isolated markers were assessed by analyses of variance. Twosignificant QTL were identified on chromosomes 1 and 5 with effects of about onewithin-family residual standard deviation. One breast muscle QTL was identifiedon GGA1 with an effect of 2.0 within-family residual standard deviation.