The objective of the submitted paper in above all to review the clinical and pharmacological aspects of the etiology, principles of diagnosis and management of drug-induced undesirable skin reactions. They are encountered in 2 - 5 % of hospitalized and in more than 1 % of all treated patients. Many of them, in particular serious idiosyncratic reactions, are very rare and therefore are not recorded in the registration stage of clinical drug testing. In serious skin reactions such as e.g. toxic epidermal necrolysis or Stevens-Johnson’s syndrome the mortality varies despite modern treatment between 20 and 30 %. The main role in the identification of drug-induced undesirable skin reactions is played by the clinical doctor. However, similarly as any other undesirable drug effects, these drug-induced reactions are not an inevitable part of treatment (of the pharmacotherapeutic procedure). Their prevention, identification and therapy, because they are so frequent, involves the necessity that every physician should possess knowledge of the prescribed drug, present disease and the patient.

        Key words: drug-induced undesirable skin reactions - etiology - diagnosis - management