Tamarindus indica and Cassia fistula are traditionally important medicinal plants. Stem barks of these plants have not been much explored for their potential hypoglycemic and oxidative stress conditions. The main aim of present study was to evaluate antidiabetic activity along with renal complications and antioxidant potential of alcoholic extracts of stem barks of these plants. Alcoholic extracts of stem barks of Tamarindus indica and Cassia fistula were evaluated for anti-hyperglycemic effect in alloxan-induced diabetic rats. Biochemical parameters including blood glucose, serum cholesterol, triglycerides, serum albumin, total protein and creatinine were studied. Antioxidant potential in DPPH, nitric oxide and hydroxyl radical induced in vitro assay methods were evaluated. Acute toxicity studies were carried out to establish the safety of the drugs according to OECD guidelines. There was a significant decrease in blood glucose level in diabetic rats treated with the alcoholic extracts of both plants. Serum cholesterol, serum triglyceride, serum creatinine, serum albumin, total proteins and body weight were recovered to normal levels at the end of the studies. Alcoholic extract of stem bark of both plants showed significant antioxidant activity in DPPH, nitric oxide and hydroxyl radical induced in vitro assay methods. Acute toxicity studies with the extracts of both plants showed no signs of toxicity up to a dose level of 2000 mg/p.o. It can be concluded from the study that Tamarindus indica and Cassia fistula stem barks possess blood glucose lowering effect along with antioxidant effect and protective effect on renal complications associated with hyperglycemia.