In the Czech Republic, mycobacteriosis is relatively rare. The low incidence probably reflects high BCG coverage rates in the Czech population. Globally, the importance of BCG vaccine has been increasing, as a result of acquired immunodeficiencies, particularly HIV infection. The presented case report describes the course of disseminated mycobacteriosis in a Vietnamese asylum seeker with newly diagnosed advanced HIV infection. In HIV patients, disseminated mycobacteriosis, most frequently caused by members of Mycobacterium avium complex (MAC), is mostly manifested in the last stage, AIDS, with extremely severe immunodeficiency, or in immune reconstitution inflammatory syndrome (IRIS), shortly after initiation of antiretroviral therapy. From the beginning, the patient's condition was complicated by multiple simultaneous severe opportunistic infections which, together with gradually progressing atypical mycobacteriosis, resulted in overall exhaustion of the organism. The adverse prognosis of these infections is significantly influenced by prolonged diagnosis based on culture detection of slow-growing mycobacteria. In the above patient, the lethal course was contributed to by resistance to commonly used antitubercular drugs which was only detected post mortem due to time-consuming susceptibility tests.