The present investigation was carried out to study the antidiabetic effect of the methanolic extract of bark of Bauhinia purpurea in Streptozotocin induced diabetic model. The antidiabetic activity was evaluated in normal & Streptozotocin induced diabetic rats. Decreased blood glucose level of the test animals showed that the extract exhibited significant antidiabetic activity when compared to diabetic control group. The results also indicated dose dependent effect. The antidiabetic activity produced by the extract might be due to the increased uptake of glucose at the tissue level or due to an increase in pancreatic beta cell function or due to inhibition of intestinal absorption of glucose.