In present study, the effect of alcoholic extract of Momordica charantia, Aegle marmelos and Eugenia jambolana was studied on serum glutamic oxaloacetate transminase and serum glutamic pyruvate transminase activities and on serum urea, total protein and albumin concentrations of streptozotocin diabetic rats. Diabetes in rats was induced by single dose of streptozotocin (30 mg/kg i. p.). On confirming the diabetes after 48 h of injection, alcoholic extracts of three plants were administered orally in doses of 250 mg and 500 mg/kg/d for 30 d. Glibenclamide (300 μg/kg/d) was used as a reference drug for comparison. Streptozotocin diabetic rats showed a significant increase in serum glutamic oxaloacetate transminase and serum glutamic pyruvate transminase activities and serum urea concentration but a significant decrease in serum total protein and albumin concentrations and albumin/globulin ratio. Oral administration of alcoholic extract of Momordica charantia, Aegle marmelos and Eugenia jambolana in daily doses of 250 mg and 500 mg/kg for a period of 1 mo produced dose- and duration-dependent decrease in serum glutamic oxaloacetate transminase and serum glutamic pyruvate transminase activities as well as decrease in serum urea concentration and restored the serum total protein and albumin concentration and albumin/globulin ratio to a great extent in streptozotocin diabetic rats. The beneficial effects of these plants in 500 mg/kg dose in streptozotocin diabetic rats were comparable to that of glibenclamide (300 μg/kg), a standard oral hypoglycaemic drug used in clinical practice.