This study aimed to compare fatty acid composition and lipid oxidation of meat of Barbarine lambs fattened on pasture improved by Medicago Arborea (P) or indoor (B) with hay and concentrate. The two groups received 400 g of concentrate. Fattening lambs under pasture decreased the level of palmitic acid C16:0 (-13.7%) and increased the levels of n-3 PUFA (+86.2%). Levels of stearic acid (C18:0), saturated fatty acids, unsaturated fatty acids, n-6 PUFA were not modified (P > 0.05). The activity of the antioxidant enzymes SOD and GPx did not change, whereas that of catalase was higher for P lambs. Moreover, the level of vitamin E was higher (4.60 vs.1.42: P<0.00l) and the malondialdehyde content was lower for P lambs (0.29 vs.1.25: P < 0.00l). These results showed that meat of lambs fed on pasture improved by Medicago Arborea presented a high nutritional quality and a higher stability during storage.