Objective: The aim of this study was to evaluate the pharmacological effects of an aqueous extract of leaves, flowers and pods of Crotalaria retusa (Fabaceae) on the blood glucose levels of streptozotocin-induced diabetic rats. Results: The phytochemical test revealed the presence of polyphenols, flavonoids, catechin and gallic tannins, quinonic compounds, alkaloids, sterols and polyterpenes. However, saponins were not detected in the aqueous extract of Crotalaria retusa. Administration of the aqueous extract of Crotalaria retusa at doses of 1000 and 600 mg/kg body weight resulted in a significant decrease in blood glucose levels in diabetic rats from day 28 until the end of treatment (84 days). The aqueous extract of Crotalaria retusa appears to have antidiabetic properties. These results would justify the use of this plant in traditional medicine for the treatment of diabetes.