Abstract: Evaluation of antidiabetic and hypolipidaemic activities of ethanolic stembark extract of Mammea africana in rats was carried out. Treatment of streptozotocin diabetic rats with the extract caused a significant (p< 0.01) reduction in fasting Blood Glucose Levels (BGL) of the diabetic rats both in acute study and prolonged treatment (2 weeks). The activity of the extract was comparable to that of the reference drug, glibenclamide. M. africana treatment showed considerable lowering of serum total cholesterol, triglycerides, LDL cholesterol, VLDL cholesterol and an increase in HDL cholesterol in the treated diabetic group. This results suggest that the stembark extract of M. africana possesses antidiabetic and hypolipidaemic effect on streptozotocin induced diabetic rats.