Abstract: Background and Objective: Parsley including flavonoids, tocopherol, coumarins carotenoids and ascorbic acid offers healthy amounts of potassium and iron. These phytochemicals improve total antioxidants capacity and these suppress destructive oxygen free radicals and prevent oxidative stress which is due to potassium bromate. The present study aimed to clarify the effect of adding parsley as an antioxidant on Potassium Bromate-fed Wister albino rat. Materials and Methods: A total of twenty four rats 60 day sold were randomly assigned to four treatment groups. Group 1 was fed untreated diet and served as negative control group. Potassium bromate was thoroughly mixed with the normal diet and fed to rats at 600 mg kg–1 (Group 2) and served as positive control group. Parsley was thoroughly mixed with the normal diet and fed to rats at 20 mg kg–1 (Group3); while Group 4 was fed a diet containing 600 mg kg–1 potassium bromate and 20 mg kg–1 parsley. All the four groups were regularly observed for 60 days. Results: The results revealed that there was no death throughout the experimental period (60 days). There was no significant change in the body and organs weights of all groups during the first 30 days but there was a significant decrease in body weight and a significant increase in kidney, liver and brain weights for the group treated with 600 mg kg–1 of potassium bromate only. There was no significant lesion seen in the growth of liver, kidney, spleen and brain in rats fed diet containing 20 mg kg–1 of parsley (Group 3) and in rats fed a diet containing 20 mg kg–1 of parsley mixed with 600 mg kg–1 potassium bromate (Group 4) compared with the negative control Group (Group 1). Significant increases of urea, creatinine and albumins levels besides significant decreases in Packed Cell Volume (PCV), Hemoglobin (HB) and Red Blood Cell (RBC) were observed in group treated with 600 mg kg–1 body weight of potassium bromate diet. Besides, there were significant increases (p<0.05) in Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) in the group treated with 600 mg kg–1 body weight of potassium bromate diet. On the other hand, PCV, RBC and Hb were significantly increased (p<0.05) by adding 20 mg kg–1 of parsley (Group 3) and 20 mg kg–1 parsley with 600 mg kg–1 potassium bromate (Group 4) compared with the control (Group 1). However, cholesterol, creatine and urea were significantly decreased (p<0.05) for Group 3 and Group4 as compared to Group 1. The level of total protein and albumin as well as AST did not change within 60 days. Histopathological changes showed that there was a congestion of liver beside a marked demyelination changes in the brain (brain oedema) of rats fed with 600 mg kg–1 of potassium bromate but there was no congestion in liver of rats fed with a diet containing 600 mg potassium bromate plus 20 mg kg–1 parsley. Conclusion: Parsley is a good source of phenolic compound and vitamin C; hence, the antioxidant activity of parsley played an important role in the protection against disorders caused by oxidative damage through delaying or inhibiting the initiation or propagation of oxidative chain reactions.