<p>1. The aim of this study was to examine the effect of yeast cell wall (YCW) on performance and physiological responses of broiler chickens under subclinical necrotic enteritis challenge.</p><p>2. Six treatments in a 2 × 3 factorial arrangement (non-challenged or challenged plus no supplement, YCW or antibiotics (AB)) was used. Each treatment was replicated eight times with 12 birds per replicate. The treatments included: (1) Positive control (PC; no additive, not challenged); (2) Negative control (NC; no additive, with challenge); (3) YCWN = yeast cell wall (2.0 g/kg diet, not challenged; (4) YCWC = yeast cell wall (2.0 g/kg diet, challenged); (5) ABN = zinc bacitracin 50 ppm + Salinomycin 60 ppm, not challenged); (6) ABC = zinc bacitracin 50 ppm + Salinomycin 60 ppm, challenged).</p><p>3. Eimeria challenge at 9 d of age did not affect feed intake (FI), body weight gain (BWG), FCR or liveability at 10 d. The BWG and FCR at 10 d were greater (P < 0.05) in birds fed YCW or AB (AB) diets relative to the PC or NC groups. On 24 and 35 d, FI, BWG, FCR and flock uniformity (28 d) were greater (P < 0.05) in the challenged groups fed YCW or AB diets compared to NC group.</p><p>4. Supplementation with YCW ameliorated the negative effects of NE on liver, spleen and bursa weight of birds.</p><p>5. Necrotic enteritis challenge decreased (P < 0.05) caecal <i>Lactobacillus</i> and <i>Bifidobacterium spp.</i> counts, and increased ileum lesion score and caecal <i>Clostridium perfirngens</i> counts. This was reversed by the addition of either YCW or AB.</p><p>6. Supplementation with YCW and AB resulted to a greater (P < 0.05) dressing percentage and meat yield (35 d).</p><p>7. The results indicated that YCW plays a vital role in improving the physiological response and performance of broiler chickens under subclinical necrotic enteritis challenge.</p>