Cimetidine may have hepatoprotective effects. We looked for the impact of cimetidine on the hepatic changes induced by carbon tetrachloride. Male Wistar-Bratislava albino rats were randomized into four groups. Group I, control (C) received physiologic saline solution (PSS) for 3 days. Group II (CT) received PSS but the last administration being followed by a carbon tetrachloride (CT) subcutaneous (sc) injection. Group III (CT+CM) received Cimetidine (CM); at the last dose of CM there was an injection of CT as for group II. Group IV was treated only with CM. The rats were weighted at the beginning of the treatment and at the moment of the euthanasia. Blood sampled were collected. The organs were removed and weighted. A sample of left lobe of the liver was taken for histological analysis. We have analysed morphometric characteristics of the organs, histological and biochemical changes. The acute hepatotoxicity effect of CCl4 in rats after a single dose was demonstrated after 24 hours. CCl4 (group II) increases the relative weight of the liver and histologically induces fatty dystrophy and extended centrilobular necrosis. The increase of ASAT and ALAT were massive. The preventive administered cimetidine, associated with CCl4 (group III) has partially hepatic protection. The fatty infiltration is not present and the focal centrilobular necrosis is less extended. The effect of hepatic cytolysis enzymes is remarkable. Acute administering at rats, CCL4 has a characteristic hepatotoxicity spectrum, induces fatty dystrophy, hepatic centrilobular necrosis and massive increases of transaminases. Cimetidine in subacute treatment, preventive, for 3 days has protective action relative to CCl4.