Introduction:
The epidemic of human immunodeficiency virus has had a tremendous effect on the epidemic of tuberculosis. Together with the spread of HIV, a great increase has been observed in morbidity due to tuberculosis, both in endemic countries and in those where earlier, as a result of treatment, the frequency of occurrence of tuberculosis had decreased. In 2018, the WHO data demonstrated that the EECA region was the only region worldwide where the epidemics of HIV was still rapidly increasing. The EECA region still struggles with a serious epidemic of tuberculosis.

Material and methods:
Materials and method. The research method applied was comparative analysis of the results of own study and studies by other researchers, concerning the effectiveness of tuberculosis prophylaxis in patients with HIV/AIDS when treated with isoniazid.

Results:
Results. In own study, it was found that primary morbidity among patients administered isoniazid significantly decreased within 5 years. Incidence rates of primary morbidity were significantly lower than among patients who had not received isoniazid. Relevant studies conducted worldwide, in many cases differed from own study with respect to both the results and approach to the problem, by country or selection of the type of patients participating in the study. However, in all studies, isoniazid was generally a safe and well-tolerated drug, without special side-effects.

Conclusions:
Conclusions. All studies analyzed concerning the effectiveness of tuberculosis prophylaxis in patients with HIV/AIDS treated with isoniazid, confirmed the effectiveness of this drug. In the compared studies, applied isoniazid preventive therapy showed no difference in effectiveness according to its duration. Analyzed studies showed similar effectiveness also with respect to a decrease in mortality among patients with TB/HIV/AIDS