A detailed quantitative trait locus (QTL) analysis of growth and fatness datafrom a three generation experimental cross between Large White (LW) and Meishan(MS) pig breeds was carried out to search for sex x QTL interactions, imprintingeffects and multiple linked QTLs. A total of 530 F(2) males and 573 F(2) femalesissued from 6 F(1) boars and 23 F(1) sows were typed for a total of 137 markerscovering the entire porcine genome. Nine growth traits and three backfatthickness measurements were analysed. All analyses were performed using linecross regression procedures. A QTL with sex-specific expression was revealed inthe proximal region of chromosome 8, although some confusion between herd andsex effects could not be discarded. This previously undetected QTL affected malegrowth during the fattening period, with a favourable additive effect of the LWallele. The analyses also revealed the presence of two linked QTLs segregatingon chromosome 1, affecting growth traits during the post-weaning period. Thefirst QTL, previously detected using a single QTL model, was located at the endof the q arm of chromosome 1 and had a favourable MS allele. The second QTL hada favourable LW allele and was located in the proximal extremity of the q arm ofchromosome 1. Suggestive genomic imprinting was found in the distal region ofchromosome 9 affecting growth during the fattening period.