Background: Leaf extracts of Senna siamea and Eucalyptus citriodora have been used to treat a range of ailment in many communities. Because the drug is unrefined, they may have some untoward effects on the animals. Objective: The objective of the study was to determine the effects of oral administration of aqueous leaf extracts of Senna siamea and Eucalyptus citriodora on some hematological parameters in healthy albino rats. Methods: Methods: Twenty-five (25) albino rats of both sexes weighing between 60 - 110g were assigned into five different groups with five rats each. Daily doses of 100, 200, 300 and 400mg/kg body weight of the plant extract mixture (ratio1:1) were given orally to groups II, III, IV and IV respectively for 21 days while group I served as control. The results of the phytochemical screening for Senna siamea showed the presence of alkaloid, flavonoid, saponins, steroids, tannins, cardiac glycosides while that of Eucalyptus citriodora showed the presence of alkaloid, saponins, tannins, anthraquinone. The results for the analysis of Red blood cell (RBC), White blood cell (WBC), Parkedcell volume (PCV), and hemoglobin were assayed using Sysmex KX-21NTM automated hematology analyzer while urea and creatinine were determined using the method of Fawcett and Scott. Results: Oral administration of aqueous leaf extract of Senna siamea and Eucalyptus citriodora at different doses in the experimental groups did not show a significant difference (p > 0.05) in the concentration of serum urea, serum creatinine, and the hematological parameters (WBC, RBC, Hemoglobin and PCV) when compared to control group except WBC which showed a significant change (p ˂ 0.05) at higher concentration of 400 mg/kg body weight of the extracts when compared to group I (control). Hematological parameters showed no significant difference (p > 0.05) when compared within the treated groups except WBC, which showed a significant difference (p ˂ 0.05) at different dose concentration of the extracts in Group II (100mg/kg) and Group IV (300mg/kg) when compared to a dose of Group V (400 mg/kg). Conclusions: This suggests that the extract at these concentrations (100, 200, 300, and 400 mg/kg) does not have any toxic effect on the renal and hematopoietic system except WBC which have a significant difference (p ˂ 0.05) at higher dose (400mg/kg) on the hematopoietic system