​Mercury is one of the environmental pollutants that could lead to a serious threat to the health of living organisms. This study was designed to determine the toxic effect of mercury chloride on hematological and immune cell levels, relative weight and tissue structure of the spleen and thymus, and concentration of mercury in these immune organs. The antioxidant protection of virgin olive oil and vitamin E against mercury toxicity in the local male rabbit Oryctolagus cuniculus was also investigated. Twenty four adult male rabbits were divided randomly into four groups, the first group was kept as a control (C-group), and three groups (M-group, O-group, and E-group) were treated respectively with 0.25 mg/kg of HgCl2, 0.25 mg/kg of HgCl2 supplemented with 3 ml/kg b.w. of virgin olive oil, and 0.25 mg/kg of HgCl2 supplemented with 3 mg/kg b.w. of vitamin E. The mercury, virgin olive oil, and vitamin E were administered orally, for 30 days-period. The results showed a decrease in red blood cell count, hemoglobin and hematocrit levels white blood cell count, lymphocytes, monocytes, neutrophils, eosinophils, and basophils in rabbits intoxicated with mercury. In contrast, the relative weight of the spleen and thymus seemed to increase compared to the control. The measurement of the quantity of mercury in organs demonstrated a notable accumulation in the spleen and thymus. The histological examination of immune organs resulted in severe morphological changes, which seemed more severe in the spleen than in the thymus. In contrast, The combined treatment with olive oil or vitamin E led to an improvement of hematological and immunological indices, demonstrating the protective role of vitamin E and the antioxidant components of olive oil against the oxidative damage caused by mercury.​