Aim of this study was to evaluate the effects of grazing on Trifolium subterraneum and Lolium multiflorum, as pure or associated crops, on the chemical composition and on the fatty acid profile of the intramuscular lipids of the meat of lambs. Forty Comisana male lambs, on average weighing 13.75±1.90kg, were divided into four homogenous groups of ten and called, in relation to the diet: group T those grazing on T. subterraneum; Group L on L. multiflorum; Group TL on adjacent monocultures of T. subterraneum and L. multiflorum (66.6 and 33.3% of surface, respectively); Group LT on adjacent monocultures of T. subterraneum and L. multiflorum (33.3 and 66.6% of surface, respectively). Every 10 days, samples of forage species ingested by grazing lambs were collected and analysed. At 90 days of age, with an average live weight of 25.44, 23.44, 24.69 and 24.75kg for T, L, TL and LT group, respectively, all lambs were slaughtered and a sample of Longissimus dorsi muscle for each animal was collected to study the chemical and acidic composition. No significant differences among the groups were observed for the growth performance and for the chemical composition of the meat. As regards the fatty acid classes, significant differences (P