This study aimed to compare between the effect of zinc oxide nanoparticles (NPs) and zinc oxide on clinical, body weight, hematological and biochemical changes in lambs. we used thirty-five Rahmani weaned lambs at Animal Production Research Institute (APRI), in Serwa station, Damietta for six weeks. The lambs were randomized into seven groups (each of five). Group A received no treatment (control). Group B (mixed small dose) received 15 ppm ZNO NPs and 15 ppm ZNO. Group C received 30 ppm ZNO NPs. Group D received 30 ppm ZNO. Group E (mixed large dose) received 30 ppm ZNO NPs and 30 ppm ZNO. Group F received 60 ppm ZNO NPs. Group G received 60 ppm ZNO. All parameters were determined at zero day before start feeding on the experimental ration and after the 6th week. Wool samples were collected for monitoring zinc, copper, and calcium.It was concluded that small doses of zinc oxide nanoparticles can be used for treatment of zinc deficiency in lambs, improving plasma and wool trace element profile and the hematobiochemical picture. It also improved the body weight gain and increased growth rate in growing lambs with minor adverse effect on liver and kidney functions.