Tin (Sn) is widely used in daily life and distributed in many tissues and nutrients. Although over-ingestion of Sn can cause health problems, relatively little attention has been given to the toxic effects of Sn in livestock health and productivity. This study was performed to investigate the toxic effects of prolonged high intake of dietary Sn on broilers. 150 one-day-old Avian broilers were randomly divided into five treatment groups, with five replicates of six birds. For 6 weeks, each group was fed a corn-soybean basal diet (BD) or BD + Sn (as SnCl2) at 120, 240, 480, or 720 mg/kg, respectively. Compared with the control, hepatic glutathione peroxidase (GPX) and superoxide dismutase (SOD) activities were significantly decreased when supplemented with Sn up to 480 mg/kg, while malondialdehyde (MDA) was increased until Sn supplementation at 720 mg/kg. Moreover, dietary Sn supplementation at 720 mg/kg decreased BW gain, feed intake, and impaired feed conversion ratio. The 720 mg Sn/kg group also increased activities of alkaline phosphatase (AKP), while decreased hemoglobin (HGB), red blood cell (RBC), and hematocrit (HCT) in the blood. Furthermore, the accumulation of Sn in various tissues was dose dependent on Sn ingestion. It was found that the tibia and feather are the two main tissues for Sn accumulation, followed by the liver, kidney, and other tissues in broilers. In conclusion, the adverse effects on broilers were induced when diets supplemented with Sn up to 480 mg/kg. Sn levels also managed to accumulate in the tibia and feather of broilers.