Cyclophosphamide, a widely-used immunosuppressive agent, may adversely affect the bone marrow. This study investigated the hematopoietic effect of the aqueous calyx extract of Hibiscus sabdariffa (HS) in cyclophosphamide-induced anaemic rats. H. sabdariffa (HS) is used locally as a hematinic concoction supposedly to raise blood level. 50g of pulverized HS leaves were boiled in 500ml distilled water and the filterate air-dried at 400C. Wistar rats (n = 24) treated as approved by LASUCOM Experimental Animal Ethics Committee, were grouped into 4: Control – water ad libitum; Group I- 200mg/Kg/day HS Extract; GP II 30mg/kg/day Cyclophosphamide for 5 days and Group III – HS 200mg/Kg/day for 30 days + 30mg/kg/day Cyclophosphamide for 5 days. Blood sample was collected directly from the heart chambers of the rats after a light anaesthesia with diethyl ether. In Group I, HS extract caused increase in Hb, PCV, RBC, platelet (PLT) count, MCV, and MCH (p<0.05) compared with Control. In Group II, there was significant reduction in Hb, PCV, RBC, MCV, MCH and PLT count (p<0.05) compared with control (p<0.05) and Group I (p<0.05). In GP III, Hb, PCV, RBC, and platelet count were similar to that of Gp I (p > 0.05). The results from this study suggest a hematopoietic potential for the aqueous leaf extract of H. sabdariffa.