Cassia auriculata, a plant native to India and popularly known as ‘avvarai’ is distributed throughout central and south India. The roots of avvarai have been used in the treatment of skin diseases, leprosy, tumors, asthma and urethrorrhea. The leaves are recommended for leprosy, skin diseases, ulcers and diabetes mellitus for more than 2000 years. The flowers and bark of Cassia auriculata are used in diabetes, urethrorrhea, nocturnal emissions and pharyngopathy. The present study is to examine the antidiabetic effect of aqueous-extracted Cassia auriculata flower powder (CFP) on steptozotocin induced diabetic rats. The antidiabetic effect of CFP extract on steptozotocin induced diabetic rats was assessed by estimating the levels of blood glucose, liver glycogen, muscle glycogen, plasma insulin, fructosefructose amine and activities of carbohydrate metabolizing enzymes, namely glucose-6-phosphatase, fructose-1,6- bisphosphatase and glucose-6-phosphate dehydrogenase. The hypoglycemic activity of these herbal powders was compared with the allopathic drugs tolbutamide and metformin. The oral administration of CFP significantly lowered the blood glucose level and restored the normal liver and muscle glycogen levels in streptozotocin-induced diabetic rats. This effect is similar to that of tolbutamide and metformin.Plasma insulin levels of diabetic rats treated with CFP and those treated with tolbutamide were found to be similar. A significant reduction of fructosamine in diabetic rats indicates that the onset of secondary complications may be delayed by CFP. CFP decreased the activity of glucose-6-phosphatase and fructose-1,6-bisphosphatase and increased the activity of glucose-6-phosphate dehydrogenase. The study concludes that the flower powder of Cassia auriculata are hypoglycemic and antidiabetic. CFP contains components capable of enhancing insulin secretion and mimicking the effects of insulin on glucose metabolism.