The effect of moringa leaves (Moringa oleifera) on fattening lambs, digestibility, feeding values, feed conversion, growth performance and economical evaluation were studied. The moringa leaves was included at a rate of 0, 7.5, 15 and 30% of the tested rations replacing soybean meal forming four dietary treatments. The control ration consisted of 75% concentrate feed mixture + 25% wheat straw. Twenty lambs with average live body weight 45 ± 1.0 kg at 10 months of age were used for 90 days feeding period. Five animals were allotted per treatment. Results revealed that moringa leaves containing high of ether extract, crude protein and nitrogen free extract (5.8, 16.5 and 52.7), respectively, but containing low of crude fiber, acid detergent fiber and nutrient detergent fiber (13.1, 20.0 and 30.3), respectively. Digestibility of all nutrients were non-significant except that ether extract (EE). Nutritive values tended to decrease as the level of moringa leaves increased. While DM intake and feed conversion tended to increase as the level of moringa leaves increased in the ration. Significant effects of blood analysis were obtained at liver and kidney function, when the level of moringa leaves increased in the rations. Economical evaluation was in favor of the 15% and 30% level supplementation regarding relative percentage of net revenue and relative percentage of cost of feed consumed. In conclusion, moringa leaves could be used economically and successfully for feeding lambs.