Background: The present study was carried out to test the antioxidant activity of lactoferrin as a dietary supplement to alleviate the effects of oxidative stress induced by mercury toxicity. Hematological and biochemical assays were employed to evaluate the ameliorating effects of lactoferrin. Methods: Sixty male Wistar rats were allotted randomly and equally into three groups; animals in Group 1 served as untreated control, animals in Group 2 were administered orally with mercuric chloride (HgCl 2 ) at the dose of 6 mg/kg bw/day, and animals in Group 3 were administered with HgCl 2 at the same dose and orally dosed with lactoferrin (400 mg/kg bw/day). Hematological indices (erythrocytic and total leukocytic counts, hemoglobin concentration%, and packed cell volume, (PCV%), and biochemical parameters (serum and homogenates of liver and kidney tissues) were assessed in all animals. Serum and tissue homogenate levels of total thiols, glutathione (GSH), catalase, and total antioxidant capacity (TAC) represented the antioxidant markers. The oxidation markers were represented by H 2 O 2 and malondialdehyde (MDA). Results: Compared to the untreated control group, animals in Group 2 (administered with HgCl 2 ) exhibited significantly increased levels of serum enzymes (alanine transferase (ALT), aspertate transferase (AST), and alkaline phosphatase), urea, blood urea nitrogen, creatinine, H 2 O 2 , and MDA. These animals showed significantly decreased levels of erythrocytic and total leukocytic counts, hemoglobin concentration, PCV%, total proteins, total thiols, GSH, catalase, and TAC. The hematological and biochemical changes were comparatively reversed toward the control levels in animals of Group 3 (administered with HgCl 2 and orally dosed with lactoferrin). The reversed levels of hematological and biochemical parameters were significantly different compared to Group 2. Conclusions: Based on the encountered amelioration of the assayed hematological and biochemical parameters in animals treated with HgCl 2 and given lactoferrin, it could be concluded that lactoferrin as a dietary supplement might function as an efficient antioxidant to alleviate the oxidative stress induced by mercury toxicity.