A quantitative trait locus (QTL) analysis of growth and fatness data from athree-generation experimental cross between Meishan (MS) and Large White (LW)pig breeds is presented. Six boars and 23 F1 sows, the progeny of six LW boarsand six MS sows, produced 530 F2 males and 573 F2 females. Nine growth traits,i.e. body weight at birth and at 3, 10, 13, 17 and 22 weeks of age, averagedaily gain from birth to 3 weeks, from 3 to 10 weeks and from 10 to 22 weeks ofage, as well as backfat thickness at 13, 17 and 22 weeks of age and at 40 and 60kg live weight were analysed. Animals were typed for a total of 137 markerscovering the entire porcine genome. Analyses were performed using two intervalmapping methods: a line-cross (LC) regression method where founder lines wereassumed to be fixed for different QTL alleles and a half-/full-sib (HFS) maximumlikelihood method where allele substitution effects were estimated within eachhalf-/full-sib family. Both methods revealed highly significant gene effects forgrowth on chromosomes 1, 4 and 7 and for backfat thickness on chromosomes 1, 4,5, 7 and X, and significant gene effects on chromosome 6 for growth and backfatthickness. Suggestive QTLs were also revealed by both methods on chromosomes 2and 3 for growth and 2 for backfat thickness. Significant gene effects weredetected for growth on chromosomes 11, 13, 14, 16 and 18 and for backfatthickness on chromosome 8, 10, 13 and 14. LW alleles were associated with highgrowth rate and low backfat thickness, except for those of chromosome 7 and to alesser extent early-growth alleles on chromosomes 1 and 2 and backfat thicknessalleles on chromosome 6.