The present experiment was designed to determine the effect/s of yeast and its derivatives on meat yield and haematological indices of broiler chickens challenged with Salmonella lipopolysaccharide (a component of Salmonella bacterial cell wall). Eight diets based on maize and soybean were offered to 432 Ross 308 broiler chickens in a 35 days experiment. Each dietary group had six replicates having nine birds each. The eight treatments groups consisted of a negative control (NC) (without supplementation and not challenged); positive control (PC) (without supplementation + LPS challenged); whole yeast + LPS challenged (WYC); yeast cell wall + LPS challenged (YCWC); yeast glucan + LPS challenged (YGC); yeast manno-protein + LPS challenged (YMPC); zinc bacitracin + LPS challenged (ZNBC); Salinomycin + LPS challenged (SalC). All yeast treatments were included at 2 g/kg diet while zinc bacitracin and Salinomycin were included at 0.03 and 0.05 g/kg diet, respectively. At d24, mean corpuscular volume, mean corpuscular haemoglobin concentration, and counts of eosinophils, neutrophils, basophils, red blood cell, haemoglobin and platelets were not significantly affected (P > 0.05) by LPS challenge. Birds in the PC group had approximately 25 % (P < 0.05) increase in the white blood cell (WBC) count compared to birds in the NC group. However, supplementation with WYC, YCWC YGC, YMPC, and ZNBC, resulted to a lower (P < 0.05) WBC count compared to birds in the PC group. Birds in the SalC and PC groups had similar (P > 0.05) WBC counts. Relative to birds in the NC group, birds in the PC group had increased (P < 0.05) lymphocyte and monocyte counts of 20% and 26%, respectively. The WYC, YCWC, YGC, YMPC and ZNBC-supplemented groups had lower (P < 0.05) lymphocyte count of 12% and monocyte count of 13%, compared to birds in the PC group. However, it was observed that birds in the SalC group had similar lymphocyte and monocyte counts to birds in the PC group. Dressing %, the weight of breast, thighs and drumsticks at d35 were depressed by LPS inoculation by approximately 14, 21, 14 and 3.5% (P < 0.05) in the PC group compared to the NC group. However, supplementation with WY, YCW, YG, YMP, ZNB and Sal in the challenged groups improved (P < 0.05) the dressing %, weight of the breast, thighs and drumsticks relative to the PC group. This present study shows that whole yeast and its derivatives can improve meat yield of broilers and, through its effect on white blood cell, lymphocyte and monocyte counts, may be associated with an amelioration of stress induced by Salmonella lipopolysaccharide in broiler chickens. This study also shows that autolyzed yeast, yeast cell wall, and its enzymatically hydrolyzed components when supplemented at 2g/kg diet may serve as a suitable alternative to in-feed antibiotics in broiler production.