AIM: To investigate the effects of Nigella sativa L (NS) and Urtica dioica L (UD) on lipid peroxidation, antioxidant enzyme systems and liver enzymes in CCl4-treated rats. METHODS: Fifty-six healthy male Wistar albino rats were used in this study. The rats were randomly allotted into one of the four experimental groups: A (CCU-only treated), B (CCU+UD treated), C (CCU+NS treated) and D (CCl4+UD+NS treated), each containing 14 animals. All groups received CCU (0.8 mL/kg of body weight, sc, twice a week for 60 d). In addition, B, C and D groups also received daily i.p. injections of 0.2 mL/kg NS or/and 2 mL/kg UD oils for 60 d. Group A, on the other hand, received only 2 mL/kg normal saline solution for 60 d. Blood samples for the biochemical analysis were taken by cardiac puncture from randomly chosen-seven rats in each treatment group at beginning and on the 60th d of the experiment. RESULTS: The CCl4 treatment for 60 d increased the lipid peroxidation and liver enzymes, and also decreased the antioxidant enzyme levels. NS or UD treatment (alone or combination) for 60 d decreased the elevated lipid peroxidation and liver enzyme levels and also increased the reduced antioxidant enzyme levels. The weight of rats decreased in group A, and increased in groups B, C and D. CONCLUSION: NS and UD decrease the lipid peroxidation and liver enzymes, and increase the antioxidant defense system activity in the CCl4-treated rats. AIM: To investigate the effects of Nigella sativa L (NS) and Urtica dioica L (UD) on lipid peroxidation, antioxidant enzyme systems and liver enzymes in CCl4-treated rats. METHODS: Fifty-six healthy male Wistar albino rats were used in this The rats were all allotted into one of the four experimental groups: A (CCU-only treated), B (CCU + UD treated), C (CCU + NS treated) and D (CCl4 + UD + NS treated) All groups received CCU (0.8 mL / kg of body weight, sc, twice a week for 60 d). In addition, B, C and D groups also received daily ip injections of 0.2 mL / kg NS or / and 2 mL / kg UD oils for 60 d. Group A, on the other hand, received only 2 mL / kg normal saline solution for 60 d. Blood samples for the biochemical analysis were taken by cardiac puncture from randomly chosen-seven rats in each treatment group at beginning and on the 60th d of the experiment. RESULTS: The CCl4 treatment for 60 d increased the lipid peroxidation and liver enzymes, and also decre ased the antioxidant enzyme levels. NS or UD treatment (alone or combination) for 60 d decreased the elevated lipid peroxidation and liver enzyme levels and also increased the reduced antioxidant enzyme levels. The weight of rats decreased in group A, and increased in groups B , C and D. CONCLUSION: NS and UD decrease the lipid peroxidation and liver enzymes, and increase the antioxidant defense system activity in the CCl4-treated rats.