BACKGROUND: Use of more efficient sources of zinc (Zn) in corn-soybean basal diet improves the productivity in the absence of growth promoters. OBJECTIVE: This study aimed to compare the effects of different forms of Zn (hydroxychloride: OHCl, oxide nanoparticles: ONPs) on performance and physiological parameters in broiler chickens. METHODS: Treatments included control (without use of ZnOHCl and ZnONPs) and three levels of zinc (40, 80 and 110 mg/kg of diets) as either ZnOHCl or ZnONPs. RESULTS: The body weight gain and feed conversion ratio for broilers fed with all levels of ZnOHCl, respectively, were greater and smaller than those of ZnONPs and control groups in the entire experiment (p < 0.05). Broilers fed with 110 mg ZnOHCl/kg benefited from the highest anti-Newcastle antibody titre and the lowest breast drip loss, whereas the heaviest relative weight of lymphatic organs and the smallest number of breast muscle pH were relevant to chickens fed with 110 mg ZnONPs/kg (p < 0.05). All levels of either ZnOHCl or ZnONPs caused better humoral immunity and the villus height:crypt depth than the control group (p < 0.05). However, all treatments had a similar effect on the relative weights of internal organs, the heterophil:lymphocyte, anti-influenza antibody titre, percentages of fat, dry matter and crude protein of breast meat, intestinal microbiota and serum biochemistry of broilers (p > 0.05). CONCLUSION: To sum up, supplementation of ZnOHCl in broilers' diets up to 110 mg was more efficient than ZnONPs in most responses relevant to immunology, growth performance and meat quality.