This study was conducted to investigate the effect of feeding different levels of protected fat on the digestion coefficients, nutritive value, ruminal and some blood parameters, and productive performance of Ossimi lambs. Three levels of protected fat (0, 4 and 8%) were used  to cover 0, 10.80 and 19.98% of the total energy of the formulated rations, respectively. Twenty four Ossimi lambs averaging initial live body weight of 32.39±0.63 kg and aging 5-6 months were  chosen and divided into three similar groups (eight  animals each). Animals in all groups were fed on iso-nutrigenous complete mixed ration for 112 days as an experimental period.. Results indicated that animals fed rations containing protected fat increased (P<0.05) digestibility coefficients of DM, OM, CP, EE and NFE than  those fed control ration. High level of protected fat (8%)  improved (P<0.05) the nutritive value as TDN and DCP than those fed control ration, being 61.35, 66.84 and 72.07% for TDN and 8.87, 9.32 and 9.96% for DCP in lambs fed 0, 4 and 8%protected fat diets, respectively. Concentration of ammonia-N and total VFA's increased (P<0.05) by increasing protected fat level at different post-feeding times. The differences in concentration of albumin, globulin and cholesterol in blood plasma was not affected significantly by the experimental rations, but concentration of total proteins, triglycerides and total lipids increased (P<0.05) in lambs fed 8% protected fat as compared to control lambs. Average daily gain was 241, 262, and 282 g/head for animals fed 0, 4 and 8% protected fat rations (P<0.05). Also, Animals fed 8% protected fat ration showed the best feed efficiency expressed as kg DM/kg gain (4.550), while those fed 4% protected fat ration recorded the best efficiency as TDN or DCP (3.172 and 0.443), respectively. Animals fed 8% protected fat showed the highest revenue and economical efficiency, being 5.059 and 2.498, respectively.