This study investigated the antioxidant properties of the fractions of the methanolic extract of Ocimum basilicum (OB) and their effects on the hematological parameters of acetaminophen-induced albino rats. Using vacuum liquid chromatography, the methanolic extract of OB was separated into four fractions (i, ii, iii, and iv) and studied using the DPPH and FRAP assays. Selected fractions ii and iv with the highest antioxidant activities for the animal study. Forty-two albino rats were divided into seven treatment groups (GP) of six animals each, subdivided into three replicates with two rats each. For seven days, rats in GP1 and GP2 were administered water and silymarin (1000mg/kg), gave those in GP4 and GP5 500mg/kg and 1000mg/kg of fraction ii, respectively, while gave those in GP6 and GP7 500mg/kg and 1000mg/kg of fraction iv respectively. Rats in GP3 were administered 750mg/kg of acetaminophen (per os) on day eight only. The results showed that, in comparison with the control groups (1, 2, and 3), rats in GRP4 showed increased (P< 0.05) hemoglobin concentration and total WBC count while GRP5 had increased (P< 0.05) PCV and MCV. Rats in GRP 6 showed increased (P< 0.05) MCV and MCHC compared to the control group, while those in GRP7 showed decreased (P< 0.05) PCV and MCV compared with the positive control. It was concluded that the free radical scavenging activity of methanolic extract fractions of OB increased in a dosedependent manner and high doses (1000mg/kg) of fraction ii showed increased hematopoietic activity.