ABSTRACT A multitude of stressors exists in broiler chickens including oxidative stress and inflammation response. Both oxidative stress and inflammation response can activate apoptosis. Melatonin (ML) is a potent antioxidant and inflammatory agent. This study evaluated the effect of melatonin on oxidative stress, inflammation cytokines, biochemical parameters and growth performance in broiler chicken under induced stress by dexamethasone. Three hundred 1-day old broiler chicks were randomly distributed to four treatments as follows: positive control (without DEX), negative control (NC, with DEX) and NC + 30 and 60 mg/kg ML. Melatonin supplementation at the level of 60 mg improved the growth performance, and antioxidant status of stressed birds. The DEX-induced effect on IL-6 and IL-10 was ameliorated by ML supplementation. The heterophil, and activities of AST, ALT and ALP were decreased by ML supplementation. This implies that dietary ML may be useful for ameliorating the negative effect of stress in broiler chickens.