We investigated the antidiabetic activity of Pistacia terebinthus (PT) extracts in streptozotocin (STZ) induced diabetic rats. We used 40 Wistar albino male rats divided into five groups: control (C), diabetes (DM), diabetes + acarbose (DM + AC), diabetes + PT (DM + PT) and PT. DM was established by intraperitoneal injection of STZ. Immunohistochemistry revealed that STZ reduced insulin immunoreactivity in the pancreas of the diabetic rats. To the contrary, insulin immunoreactivity in the pancreatic beta cells of PT treated diabetic rats was increased significantly. Decreased levels of blood glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), glucose, total triglyceride (TG), total cholesterol (TC), high density lipoprotein (HDL) and low density lipoprotein (LDL) were found in the PT supplemented diabetic group. Also, malondialdehyde (MDA) and antioxidant defense system enzyme levels were normalized in the DM + PT group. PT exhibited a protective effect on liver, kidney and pancreas that had been damaged by STZ induced DM.