The aim of the study was to analyze the incidence and prevalence of opportunistic diseases and comorbidities in patients admitted in the intensive care unit. Materials and methods. A specialized intensive care unit (ICU) for patients with severe HIV infection was set up in 2014 at the infectious diseases 2nd state hospital Moscow. It provides intensive care and treatments for HIV patients with severe co-morbidities and opportunistic infections. Retrospective analysis of medical records from 2014-2016 was carried out. Also carried out was a comparative study of the most common presentation of secondary diseases with available data of HIV patients in Russia from 1993-1997. Results. The number of patients treated increased from 455 to 852, and the death rate in the department decreased from 64.8 to 50.2% since it began operating. The opportunistic infections noted were cytomegalovirus, pneumocystis pneumonia, esophageal can-didiasis, tuberculosis and toxoplasmosis of the brain. The most common comorbidities were chronic hepatitis C and mixed form of chronic hepatitis with cirrhosis complications. Despite the vast diagnostic possibilities, bacterial pneumonia and encephalitis of unknown origin significantly occurred. Comparative study of secondary disease since the early 1990s revealed a significant increase in cerebral toxoplasmosis (from 1.7 to 10.4%), pneumocystis pneumonia (from 5.2 to 16.0%) and encephalitis of unspecified etiology (from 13.8 to 39.4%) Conclusion. Disease severity among HIV patients is increasing. CMV and pneumocystis pneumonia were predominant opportunistic diseases. There were significant changes in the presentation of secondary diseases compared to data from 1993-1997. © 2018 Media Sphera Publishing Group.All Rights Reserved.