An experiment was carried out to study the effect of sex and rearing system on growth performance and carcass quality of milk-fed Assaf lambs. 24 lambs, (12 males-12 females) were used. They were slaughtered at 10 kg body weight. Half of them remained with their mothers (NR: suckling lambs), the other twelve (AR: artificially reared lambs) were removed from the ewes within 24-36 hours of birth, housed in individual pens and fed ad libitum twice daily with reconstituted cow's milk. There was no significant effect of sex on growth rate and carcass quality, except for perirenal-retroperitoneal-fat. Concerning the effects of the rearing system, NR lambs showed a significant higher growth rate and consequently a lower age at slaughter than AR lambs. NR lambs also showed higher values of fatness score and subcutaneous and intermuscular fat in the shoulder. The rearing system did not affect either carcass weight or dressing proportion. Regardless of sex or rearing system effects, carcass quality was in general suitable for Spanish market.