Birth weight and within-litter variation in birth weight are important economic traits in pig production. Genetic selection for large litters during the last decades has lowered mean birth weight, which mainly results from a higher competition of the fetuses in utero reflected also by an inverse correlation of birth weight and litter size (e.g. Milligan, Fraser, & Kramer, 2002; Quiniou, Dagorn, & Gaudre, 2002). Low birth weight, however, is associated with decreased survival and lower postnatal growth rates (e.g. Herpin, Damon, & Le Dividich, 2002; Milligan et al., 2002; Pond & Mersmann, 1988; Quiniou et al., 2002; Ritter & Zschorlich, 1990). In addition, pigs at market weight originating from piglets of low birth weight develop a lower carcass quality in terms of higher fat deposition and lower lean accretion compared with their middle or heavy weight littermates (Bee, 2004; Gondret et al., 2006; Hegarty and Allen, 1978; Kuhn et al., 2002; Poore & Fowden, 2004; Powell and Aberle, 1980, 1981; Rehfeldt and Kuhn, 2006). Low birth weight results from intrauterine growth retardation during gestation. It has been shown previously that small piglets form a lower total number of skeletal muscle fibres during prenatal development compared with their larger littermates (Gondret et al., 2006; Handel & Stickland, 1987; Wigmore & Stickland, 1983). From recent studies, it has been suggested that it is the low number of muscle fibres, which restricts the potential of postnatal lean growth and therefore allows to deposit increased amounts of fat (Rehfeldt & Kuhn, 2006). In addition, tendencies towards lower meat quality in terms of tenderness and water holding capacity have been observed at slaughter, when the piglets were small at birth (Gondret et al., 2005; Gondret et al., 2006; Rehfeldt & Kuhn, 2006), which may be associated with accelerated muscle fibre hypertrophy because of low fibre number. The studies on the influence of birth weight mentioned above have in common, that the number of animals used in the experiments were not very large (5–32 pigs per birth weight group born to 13– 16 sows) and the variation in the traits of interest caused by the dam/litter has not always been considered in the statistical models. Therefore, this study was conducted using a larger set of pigs from 63 litters in total to re-examine the consequences of birth weight for ultimate carcass and meat quality. In order to accomplish this, the offspring (n = 378) of the 63 sows were assigned to three birth weight groups; 25% low weight, 50% middle weight, and 25% heavy weight, with runts (<800 g) being excluded. Low weight pigs exhibited the lowest postnatal growth performance, the lowest lean mass and the greatest degree of fatness in terms of perirenal fat compared with medium weight and heavy weight pigs. Only in females, but not in male castrates, the lean percentage was highest in heavy weight pigs. Characteristics of longissimus muscle technological quality declined either in low weight (pH, drip loss) or heavy weight (conductivity, lightness) compared with medium weight pigs. In contrast, intramuscular fat percentage (IMF) was highest in low weight pigs. The results suggest that the most desirable carcass composition is obtained with heavy weight pigs, whereas optimum technological pork quality, except for IMF, is achieved with medium weight pigs.