In this study, the effects of Urtica urens L. (dwarf nettle, UU) seed extract on lipid peroxidation, antioxidant and xenobiotic metabolizing enzymes in both control and carbon tetrachloride (CCl4)-treated rats were investigated. Male Wistar rats were randomly allotted into one of the four experimental groups. A (Control), B (UU-treated), C (CCl4-only treated) and D (UU+CCl4-treated), each having 5-24 animals. Some of rats in group A were treated with physiological saline, i.p. daily for 4 days; Group B were treated with UU 200 mg/kg, i.p. daily for 4 consecutive days; Group C were administered with CCl4 at dose of 10 ml/kg, i.p. for 2 consecutive days; and group D rats were pretreated with UU 200 mg/kg, i.p. daily for 4 consecutive days prior to administration of CCl4 10 ml/kg, i.p. daily for 2 consecutive days. At the end of the experimental period, rats were sacrificed, and tissues were taken. Results have indicated that treatment of rats with U. urens increased hepatic antioxidant enzymes without changing the levels of serum Lactate DeHydrogenase (LDH), ALanine aminoTransferase (ALT) and ASpartate aminoTransferase (AST). Moreover, U. urens treatment decreased the CCl4 dependent elevated lipid peroxidation and serum LDH, ALT and AST activities. Furthermore, U. urens protected the inhibitory effect of CCl4 on CYP2E1 catalyzed aniline 4-hydroxylase activities. As a result, as indicated by these in vivo data, U. urens seed extract contains constituents protecting liver against hepatotoxic effects of CCl4.