Many plants of genus Salvia are used for food products and medicine. The present study was designed to examine the antidiabetic effect of Salvia syriaca ethanolic extract in normal and streptozotocin-induced diabetic rats. Diabetes in rats was induced with a single injection of streptozotocin (70 mg/kg body weight) by intraperitoneal route. Salvia syriaca ethanolic extract (50, 100, and 200 mg/kg body weight) were administrated orally for 30 days. After 30 days, rats were anesthetized and blood samples were collected. Serum glucose, insulin, triglycerides, total cholesterol, urea, uric acid, creatinine, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in normal and streptozotocin-induced diabetic rats were evaluated. Oral administration of Salvia syriaca ethanoic extract for 30 days exhibited a significant reduction in serum glucose, triglycerides, total cholesterol, urea, uric acid, creatinine, AST, ALT and increased plasma insulin in streptozotocin-induced diabetic rats. The administration of extract did not change these serum parameters in normal rats. It is concluded that Salvia syriaca has antidiabetic effect in rats and the plant should be considered as an excellent candidate for future studies on diabetes mellitus.