Abstract: The anti-malaria effect of the aqueous extracts of Alstonia boonei was assessed and its influence on hematological profiles in treated and untreated mice. It is clear that Alstonia boonei showed marked antimalaria effects in a dose seeming fashion from the percentage chemosuppression and percentage parasitemia computed. The hematological indices of the mice assessed in this study includes the levels of White Blood Cells (WBC), Red Blood Cells (RBC), Hemoglobin (Hb), Packed Cell Volume (PCV), Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin Concentration (MCHC), platelets, lymphocytes and neutrophils of the different groups of mice. The untreated group of mice infected with the chloroquine -sensitive strain of Plasmodium berghei recorded a significant (p<0.05) reduction in PCV, Hb, RBC, MCV and neutrophils observably from day 8-14 post infection while lymphocytes, WBC and platelets counts increased significantly (p<0.05) from day 8-14 postinfection in infected, untreated mice. Administration of the aqueous extracts of A. boonei at the different dosages 100, 200, 400 and 800 mg kg-1, respectively to mice infected with P. berghei resulted in the normalization of hematological indices in the groups of mice infected and treated with the plant extracts when compared with the data obtained for the experimental control groups of mice. Although, it was observed that the MCV and MCHC values did not vary significantly in the treated groups when compared with experiment control groups. However, the plant extract indeed possess anti-malaria effect and our data on its influence on blood profiles during infection and treatment clearly illustrates its protective effect in malaria infection.