e evaluated the fects of different levels of dietary silver nanoparticle (AgNP) powder on performance, intestinal microflora, carcass traits and blood parameters of broiler chickens. Three hundred seven-day-old Ross broiler chicks were randomly divided into five groups, each group replicated three times with 20 birds per replication. Chickens were fed the basal diet with 2.5, 5, 10 and 20 mg AgNPs per kg feed. Dietary inclusion of AgNPs improved the final body weight, cumulative weight gain and feed conversion ratio. The best broiler performance, carcass traits, and relative organ weights were observed in the group supplemented with 2.5 ppm AgNPs. Increasing the AgNP dose resulted in a significant decrease in the caecal lactose positive and enterococci bacteria populations, while lactobacilli counts were numerically increased. The silver residues in the breast and thigh muscle significantly increased (p < .05) in a dose-dependent manner. Dietary inclusion of AgNPs induced dose-dependent lesions in liver, kidney, spleen and duodenum tissues involving degeneration, necrosis, mononuclear infiltration and focal aggregation of inflammatory cells. In conclusion, despite its potential positive impacts on growth performance, carcass traits and caecal microbial population diversity at a dose of 2.5 ppm, dietary inclusion of AgNPs had the following negative effects on broilers: 1) silver residues in breast and thigh muscle, which may result in AgNPs transmission to consumers, and 2) cytotoxicity in intestinal, liver, spleen and kidney cells in a dose-dependent manner. Therefore, we suggest the use of lower doses of AgNPs (< 2.5 ppm diet) in poultry production in the future studies