Potassium bromate (KBrO 3), a strong oxidizing agent, is mainly used as a flour improver; it is classified as B2 (probable human) carcinogen and health organizations start banning it. However, it is still used in bakeries in large amounts. The aim of this study was to investigate the effect of KBrO 3 administration on the tongue of adult male albino rats. Sixty adult male albino rats weighting~200 gm were divided equally into threegroups: control, experimental group I (gp I), and experimental group II (gp II). Control group received distilled water and the experimental gps. received 62 and 123 mg\kg KBrO 3 , respectively, dissolved in distilled water orally on a daily basis for 2 and 4 months. Histopathological examination of specimens in experimental groups revealed dysplastic and carcinogenic changes that were dose-and timedependent to end in the epithelial invasion of connective tissue. The immunohistochemical results showed a significant increase in the immunoreactivity of PCNA in KBrO 3 treated groups compared to the control group. In conclusion, KBrO 3 long-term administration has a carcinogenic effect, so it is considered as a risk on public health.