Drug rash with eosinophilia and systemic symptoms (DRESS) – drug-induced hypersensitivity syndrome (DIHS) is one of the serious, potentially life-threatening reactions of hypersensitivity to drugs. The clinical symptoms occur after 3 to 8 weeks from beginning therapy with some drugs (carbamazepine, dapsone, salazosulfapyridine, phenobarbital, phenytoin, allopurinol, mexiletine, minocycline). The syndrome is characterized by fever of at least 38°C, dermatitis, internal organ involvement and usually prolonged course, lasting many months. DRESS/DIHS is identified seldom and probably a proportion of cases remain in the spectrum of misdiagnosed idiopathic skin disorders, including erythroderma. In 2006 diagnostic criteria were established: 1) maculopapular rash developing > 3 weeks after starting therapy with a limited number of drugs, 2) lymphadenopathy, 3) fever (> 38°C), 4) leukocytosis (> 10 × 109/l) – atypical lymphocytosis, eosinophilia, 5) hepatitis (ALT > 100 U/l), 6) HHV-6 reactivation. Diagnosis of typical syndrome is based on confirmation of all six criteria. Current data concerning aetiopathogenesis, clinical picture, diagnostics and treatment of DRESS/DIHS are presented. Key words: drug rash, hepatitis, HHV-6 reactivation.