Background: Momordica charantia L. is a medicinal plant commonly used in the management of diabetes mellitus. Objectives: We investigated the blood glucose lowering effect of the methanolic fruit extract of the Ugandan variety of M. charantia L. in alloxan-induced diabetic albino rats. Methods: 500g of M. charantia powder were macerated in methanol and the extract administered to two groups of alloxaninduced diabetic rats. The first group received 125mg/kg, the second 375mg/kg and a third group 7mg/ kg of metformin. A fourth group received 1ml normal saline. Fasting blood glucose (FBG) levels were measured at 0.5,1,2,3,5,8 and 12 hours and compared using one-way ANOVA. Results: There was an initial rise in FBG for 1 hour after administration of extracts followed by steep reductions. Significant reduction in FBG occurred at 2 hours for 125mg/kg of extract (-3.2%, 313±25.9 to 303±25.0mg/dL, p = 0.049), 375mg/ kg of extract (-3.9%, 356±19.7 to 342±20.3mg/dL, p = 0.001), and metformin (-2.6%, 344±21.7 to 335±21.1mg/dL, p = 0.003) when compared to normal saline. The maximum percentage reduction in FBG by both extracts occurred between 3 and 12 hours post dose. Conclusions: The methanolic fruit extract of M. charantia exhibits dose dependent hypoglycaemic activity in vivo.