Drug induced liver injury (DILI) is often underdiagnosed disease with increasing incidence. In developed countries it belongs to the leading causes of acute liver failure. Risk groups are women and persons older than 60 years. The work summarizes the up to date information on diagnosis and mostly used classifications on DILI. It is quite often and serious complication of medicament therapy. DILI belongs to the most often cause of acute hepatic failure in the old age in developed countries. Diagnostic procedure includes medical history (time correlation with drug intake), clinical symptoms and blood tests. Laboratory tests may be helpful to specify immunopathogenetic origin, but negative results does not exclude diagnosis. The exclusion of other possible etiological factors is the crucial condition of diagnosis statement. Key words: DILI/drug induced liver toxicity - DILIn network - RUCAM classification.