The liver is essential for metabolism of drugs and exogenous toxins. Therefore, liver toxicity due to natural, domestic and industrial toxins or drugs is common but rarely recognised. Although thorough epidemiological data are missing, the number of cases with drug-induced liver toxicity is increasing, parallel to the growing number of drugs. Adverse hepatic reactions may present as acute or chronic liver damage. Independent from the cause and mechanism of liver damage, the clinical presentation may be either cytolytic or cholestatic. In addition, liver damage may be accompanied by a systemic hypersensitivity reaction against the applied agent. Drug- or toxin-induced liver damage includes vascular damage, induction of liver tumours and development of liver cirrhosis. The prerequisite for specialised treatment of drug-induced adverse hepatic reactions is establishing the diagnosis which is obtained by a thorough medical history taken by an experienced physician with a special emphasis on drug or toxin exposure. The diagnosis may be confirmed by additional diagnostic measures (e. g. liver biopsy) or the clinical course after exposure to the causing agent has been stopped. Only in a minority of cases a definite treatment may be available. Therefore, the main aim is to prevent chronic liver damage through early and correct diagnosis. Due to the extensive variety of possibly liver toxic drugs and chemical agents this aspect is a major challenge to physicians.