Antiretroviral therapy (ART) for HIV-positive patients allowed labeling the disease a therapeutically controlled one. The main goal of ART is to prolong patient's life and preserve its quality. This is accomplished through viral load reduction (decrease of the number of HIV-RNA copies in blood plasma), which leads to the growing numbers of CD4⁺-T-lymphocytes. However, ART can be ineffective. In 2010–1014, we conducted an observational cohort retro/prospective study aimed at learning how often ART can be ineffective from immunological (II), virological (VI) and clinical points of view. The study was carried out at the premises of the Republic Center of AIDS and Infectious Diseases (Kazan, Russia). The study included 341 adult HIV-positive patients subjected to ART at 3rd and 4th stages of disease's development, with the treatment virologically efficient at least during the first year. The observation period was 1 to 3 years. ART was considered II (immunologically inefficient) when the number of CD4⁺ increased for less than 50 cells/mcl through the year with HIV completely suppressed. VI (virological inefficiency) of ART was registered if the number of HIV RNA copies was above the definition threshold after 6 months of treatment. ART was II in 14.0–15.9 % of cases after a year of treatment and in 22 % of cases after three years. It was noted that subsequent restoration of an adequate number of T-lymphocytes CD4⁺ required they overcame the threshold of 100 cells/mcl within the 1st year of treatment. Virologically, ART was effective for 92.7 % for patients. Most (80 %) cases of VI of ART were results of patients' lax attitude towards treatment. Clinically, ART helped 91 % of patients; this result largely depended on the number participants for whom ART was II. II of ART is a risk factor, the risk being progression of the disease with active ART in the background and death of the HIV-positive individual. II of ART makes the risk of clinical progression of HIV 6.232 times higher (95 % CI 3.106–12.51).