BACKGROUND : Chronic hyperglycaemia-induced haematological changes increase the risk of cardiovascular complications in diabetic patients. The administration of insulin injection as a bolus is accompanied with increased blood viscosity, which is not recommended for patients with congestive heart failure. Momordica balsamina methanolic extract (MB) has previously been shown to possess anti-hyperglycaemic and renal dysfunction ameliorative effects; however, the haematological effects of MB have not been shown. The current study therefore, investigated the short-term effects MB on selected haematological parameters in streptozotocin (STZ)-induced diabetic rats. METHODS : Briefly, the air-dried Momordica balsamina leaves were sequentially extracted with methanol to yield a methanolic extract. STZ-induced diabetic rats were divided into untreated and treated groups with insulin (170 μg kg-1 s.c.) and metformin (500 mg kg-1 p.o.) MB (250 mg kg-1 p.o.). MB was administered twice daily for the 5-week experimental period. Blood glucose concentration was monitored weekly. Animals were sacrificed terminally. Blood and kidneys were collected for haematological and biochemical analysis respectively. RESULTS : Treatment with MB significantly decreased blood glucose concentration and improved erythropoietin secretion, thus significantly increasing red blood cell production in treated diabetic animals by comparison to untreated animals. MB also significantly improved haemoglobin concentrations and moderately increased erythrocyte indices specifically, mean corpuscular volume (MCV), mean corpuscular haemoglobin concentration (MCHC) and mean corpuscular haemoglobin (MCH) to no significance by comparison to untreated diabetic animals. MB treatment decreased the oxidative stress evoked by the induction of diabetes while improving the antioxidant status of treated animals by comparison to untreated animals respectively. CONCLUSIONS : Administration of Momordica balsamina methanolic extract protects against some injurious haematological changes induced by hyperglycaemia, which may reduce the risks of cardiovascular complications.