The aim of this investigation was to study the effect of cannabis on hematological parameters of Wistar rats induced with copper toxicity. Twenty (20) rats were randomly divided into four groups of five rats each. Group A (negative control) received water only for 15 days, Group B received copper at 200 mg/kg for five days, Group C received copper at 200 mg/kg for five days then treated with cannabis at 300mg/kg for ten days and Group D received cannabis at 300mg/kg only for ten days. All the rats were sacrificed on day sixteen and blood was collected through cardiac puncture and analyzed. Prepared slides from the heart were dehydrated using a dry air oven in xylene for 30 minutes and later mounted on the microscope and viewed using oil immersion ×1000 magnification. In a group induced with copper, we observed a decrease in PVC, RBC, and WBC. Leucopenia, lymphopenia, monocytopenia, and eosinopenia were also observed. However, there was an increase in MCHC, MCH, and MCV. The result of this study shows that copper caused changes in hematological parameters that lead to anemia, also treatment with cannabis caused a relative increase in hematological parameters which was not significant enough to reverse the effect. However, cannabis only was able to cause polycythemia.