Topicality. The search for natural remedies that would exhibit antiseptic, anti-inflammatory, detoxification, antioxidant, choleretic, hepatoprotective actions and positively influenced the entire body in order to create new medicines based on them is one of the pressing issues of modern pharmacology and pharmacy. Plants used for food can serve as a basis for new medicines.Aim. To establish a conditionally therapeutic dose of the extract from lettuce leaves in the experiment with simulated tetrachloromethane hepatitis in rats.Materials and methods. The experiments were carried out on white outbred male rats, who were simulated toxic liver damage with carbon tetrachloride (twice (every other day) at a dose of 1.0 ml/kg body weight). Euthanasia was performed using sodium thiopental on the fourth day after the introduction of carbon tetrachloride in compliance with all rules for working with vertebrate animals. For the study, extract doses of 50 mg, 100 mg, 150 mg and 200 mg per kilogram of body weight of the animal were used. The activity of lipid peroxidation was assessed by the content of TBAactive products, the activity of membrane-destructive processes - by the activity of aminotransferases (AsAT and AlAT), the state of the antioxidant system by the content of CP and catalase activity.Results and discussion. It was noted that the lesion of rats with carbon tetrachloride causes a significant (p ≤ 0.05)increase in serum levels of TBA-active products (2.1 times), ceruloplasmin (5.6 times) and aminotransferase activities. At the same time, a decrease in catalase activity is observed (by 5.8 times). The activity of AsAT and AlAT in the serum during this period increases almost equally – by 4 times. Significant changes in the studied parameters observed after application of a dose of 100 mg / kg of body weight of animals.Conclusions. A conditionally therapeutic dose of the extract is considered to be a dose of 100 mg/kg of bodyweight, which has a positive effect on the indices of lipid peroxidation, antioxidant system and cytolysis under conditions of modeled toxic hepatitis.