Summary: Dry seeds of the plant, Hunteria umbellata K. Schum (family: Apocynaceae), are highly valued in African traditional medicine in the treatment of various human diseases, including diabetes mellitus and obesity. In the present study, the hypoglycaemic and weight loss effects of 50 - 200 mg/kg of the aqueous seed extract of Hunteria umbellata ( HU ) were investigated in normal and drug-induced hyperglycaemic rats. In addition, the acute oral toxicity using the preliminary and the main tests of the Up-and-Down Procedure according to OECD/OCDE Test Guidelines on Acute Oral Toxicity was conducted. Phytochemical analysis of the aqueous seed extract was also carried out. Results showed that HU caused progressive and significant (p<0.05, p<0.01 and p<0.001) dose-related reduction in the blood glucose concentrations in normal and drug-induced hyperglycaemic rats, an effect, which was more than that of glibenclamide and mediated via inhibition of intestinal glucose uptake and adrenergic homeostatic mechanisms. HU also caused significant (p<0.05 and p<0.01) dose-dependent reduction in the average body weight of treated rats when compared to untreated rats. The acute oral toxicity study showed that the plant extract had an LD50 of 1020 mg/kg and as such slightly toxic. Results of the phytochemical analysis of HU revealed the presence of alkaloids, flavonoids, tannins and glycosides. Thus, the data generated in the present study has a strong positive correlation with its folkloric use in the treatment of suspected type 2 diabetic patients, although its use should be with great caution. Industrial relevance: The data generated in this study suggest that HU could be very useful in the management of type 2 diabetes mellitus although several further studies will still be required at identifying the active hypoglycaemic phytocomponent(s) and their possible mechanisms of action.