This research was conducted to investigate the performance of Awassi lambs in the two fattening systems in Palestine. Both systems are based in specific locations in the country with variable outcomes. A total of sixty Awassi lambs were used in the experiment. Lambs were divided into two groups of thirty lambs in each. Lambs in the first group were fed a concentrate ration similar to those fed in commercial fattening operations. Lambs in the second group were fed a barley-based diet (70% barley plus 30% legume roughage). Lambs were fed their rations for 70 days. Lambs were weighed at weekly basis. At day 42 of beginning of the feeding trial, a digestibility trial was conducted on eight of each group. A six days total collection of feed, feces and urine was performed. The performance of lambs fed the commercial fattening rations was much belter than lambs fed the barley based rations. This was observed from the performance parameters such as the total gain, average daily gain (278 vs. 146 g) and the feed conversion efficiencies. Lambs fed the commercial fattening rations had average feed efficiency of 5.5 kg while that of lambs the barley based rations was 8.8 kg. The cost of gain was significantly (P<0.05) higher in lambs fed the barley-based diets. The digestion trials showed that the dry matter and nutrients digestibility were higher for the commercial fattening rations compared to barley based rations.