The objective of the present study was to evaluate the effects of oak acorn (Quercus ilex) intake before and after weaning on lamb growth, meat properties and fatty acid (FA) composition. In total 32 Barbarine male lambs were divided into 4 groups, 8 lambs in each. Before weaning, 16 lambs were reared with their dams on range pasture; each mother-lamb pair received 400 g of barley concentrate. The other 16 were reared with their dams on forest pasture; each mother-lamb pair received 300 g of oak acorn concentrate. During the fattening period, lambs were reared in feedlot on one of the 4 dietary treatments – based on concentrate of barley alone or barley plus acorn. Both BarBar and BarAco groups received barley while suckling, and then barley and acorn, respectively, for the fattening period. AcoBar and AcoAco groups received acorn while suckling and then barley and acorn, respectively, for the fattening period. Acorn intake affected neither growth rate nor the physicochemical traits of meat (except pH measured 1 h post mortem). The sum of saturated FA was similar in all groups, whereas C18:0 was higher in AcoAco and BarAco animals (P < 0.01) than in AcoBar and BarBar (about 25 and 22%, respectively). The total monounsaturated FA and polyunsaturated FA did not differ among the groups, except C18:3n-3 which was higher in the AcoAco and AcoBar (P < 0.01) than in BarBar group (0.37 and 0.18%, respectively). The AcoAco group had the highest meat sensory parameters (tenderness, juiciness and general acceptance). So, it may be concluded that ground oak acorn can be used up to 40% in lamb diets without any unfavourable effects on growth performance or meat characteristics.