A feeding trial was conducted with fattening Awassi lambs using corrugated carton to study the nutritional effect of this by-product and to search for low cost rations. Thirty male lambs were assigned to three dietary treatments. The control diet was composed of 40% barley, 16% soybean meal, 12% wheat bran, 1% limestone, 1% salt, 1% lambs’ premix and 29% wheat straw. To each of the experimental rations, carton was incorporated instead of wheat straw at levels of 10 and 20%, respectively. Cardboard was treated with urea prior to use. The lamb feeding trial extended for a period of 40 days. Average initial live weights were 29.6, 29.9 and 29.5 kg for each of the three groups, respectively. Mean daily gains were 210, 200 and 205 g per day for each of the three groups, respectively. Average feed conversion rates were 6.3, 6.7 and 6.8 kg feed per kg gain and the feed costs per kg gain were US$ 0.94, 0.87 and 0.74 for each of the three treatments, respectively. The results of the experiment indicated that the low levels of carton in lambs fattening rations had no disadvantages on performance compared to the control ration used. The experiment showed that, under current feed prices in the Palestinian Authority, replacing up to 20% of wheat straw with carton proves to be beneficial and economically feasible.