Purpose: St. Petersburg, Russia and its surrounding Leningradskaya oblast (LO) have the high incidence of HIV-infection, involving the epidemic 1.2% of the population of LO. The cause-of-death data on HIV-infected were analyzed for better understanding the urgent clinical and public health interventions. Method: Causes of mortality in HIV type 1 infected patients in the largest infectious diseases hospital in St. Petersburg in the year 2015 and associations of prognostic factors with cause-specific mortality were analyzed. Results: Among 2,516 patients died 383 (15,2%, 257 males, 126 females; mean age 36 years; SD:7.5). Among the dead, the advanced HIV/AIDS stage (CDC category C3) was diagnosed in 319 out of 355 (92.7%). CD4-positive count varied 0-665 (median 33 cell/mcl [10;97]). In 116 (30.3%) patients HIV-infection were diagnosed for the first time. In 256 (66.8%) it lasted more than one year, but only 6 (2.3%) of them received effective antiretroviral therapy (ART). In total, 96 (25.1%) patients had started but 54/96 (56.3%) interrupted ART. The most frequent opportunistic infection was tuberculosis (n=176, 45.9%), with the generalization in 149 (38.9%) patients, caused by mono/polyresistant Mycobacteria in 40 from 47 (85.0%) analyzed cases. Tuberculosis became the main reason of death (135, 35%), following with pneumonia (n=80, 20.9%), encephalitis (n=65, 17%) and cancer (n=24, 6.7%). In total, cancers were detected in 31 (8.1%) patients. Patients with CD4>65/µL had higher risk for development of cancer (adjusted (by age and sex) OR=2.2, 95%CI:1.00-4.78) and dying from it (adjusted OR=3.2, 95%:CI). No association between cancers and gender, HIV-infection stage and duration and ART was observed. Conclusion: An active program for early detection of HIV, initiation of ART, detection of associated diseases and precancers will help prevent the development of diseases and deaths related to HIV/AIDS, which will lead to an increase in the life expectancy of HIV-infected in Russia.