The present study was carried out to investigate the antidiabetic and antihyperlipidemic properties of hydroalcoholic extract of Peganum harmala in streptozotocin-induced diabetic male rats. In an experimental study, 64 normal Wistar albino male rats (200-230 g) were randomly divided into 8 groups. Control and diabetic rats were treated with normal saline and three different doses (30, 60, and 120 mg/kg) of hydroalcoholic extract of Peganum harmala seeds for 4 weeks orally. At the end of treatment, blood samples were taken and glucose, triglycerides, total cholesterol, LDL-c, HDL-c, malondialdehyde (MDA), total antioxidant capacity (TCA), ALT, AST, GGT, bilirubin, and glycosylated hemoglobin (HbA1C) were determined. STZ-induced diabetic rats showed significant changes in the values of glucose, triglycerides, total cholesterol, LDL-c, MDA, TAC, ALT, AST, GGT, bilirubin, and HbA1C in comparison with normal rats. Administration of the extract to diabetic rats resulted in a remarkable decrease in glucose, lipid profiles, MDA, ALT, AST, GGT, bilirubin, and HbA1C levels and increase in TAC relative to diabetic group. The results of this study indicated that hydroalcoholic extract of Peganum harmala seeds possesses antidiabetic and hypolipidemic activities and could be useful in treatment of diabetes.