Blood glucose and total lipid levels were determined in streptozotocin induced diabetic rats after oral administration of an ethanol flower extract of Hibiscus rosa sinensis. A comparable hypoglycemic effect was evidenced from the data obtained after 7 and 21 days of oral administration of the extract and glibenclamide. Maximal diminution in blood glucose (41-46%) and insulin level (14%) was noticed after 21 days. The extract lowered the total cholesterol and serum triglycerides by 22 and 30%, respectively. The increase in HDL-cholesterol was much higher (12%) under the influence of the extract as compared to that of glibenclamide (1%). The hypoglycemic activity of this extract is comparable to that of glibenclamide but is not mediated through insulin release. Other possible mechanisms are discussed.