A total of two hundred and four, one day old Ross broiler chicks were randomly allotted into four dietary treatments floor pen groups (17 birds/ pen, 10 birds/m 2 ) with three replicates for each treatment. The dietary treatments were designed to feed the chick's basal diet supplemented with graded levels of Moringa oleifera leaves meal, MOLM [3%, 5%, 8% and 0% (control) MOLM]. Behavioral observation was carried out twice daily (AM,(7)(8)(9)(10)(13)(14)(15) two days a week for 6 consecutive weeks. Body weight (BW), Body weight gain (BWG) and Feed intake per pen was measured weekly, from which feed conversion ratio (FCR) was calculated. At 30 th day of age blood samples were collected to evaluate anti body titer (HI) against New Castel Diseased Virus (ND). At the end of the experiment, fear responses, differential leucocyte count, Hb and PCV were assayed as well as some carcass traits. Also, mortality rate was estimated. The obtained results showed that higher proportion of birds were engaged in feeding in groups dietary treated with 3% and 5% MOLM, while intermediate responses was shown in birds supplemented with 8% MOLM compared to control ones. The supplemented groups with MOLM showed a lower walking and standing activities than non-supplemented ones. Dietary supplementation with different levels MOLM significantly improved BW, BWG and FCR. In addition, the mortality rates for the dietary treated groups were not affected. The MOLM supplemented groups were less fearful in tonic immobility test, less stressed and had lower heterophil/lymphocyte ratio when compared to un-supplemented ones. MOLM had no effect on Hb concentration and carcass traits. PCV was significantly higher in birds fed 5% MOLM compared to control birds. Birds supplemented with 3%, 5% and 8% MOLM had significant higher antibody titre against ND compared to un-supplemented birds. In conclude, dietary supplementation of broiler chicks with MOLM up to 8% resulted in improved welfare, performance and immune response against ND.