Introduction:The objective was to identify comorbidities related to HIV-positive patients in Blumenau, State of Santa Catarina. Methods: A retrospective, descriptive observational design study which analyzed data from 424 patients assisted by the sexually transmitted disease/acquired immunodeficiency syndrome (STD/AIDS) Specialized Care Service (SCS). Results: Of 424 medical records analyzed, 388 patients presented CD4 + /CD8 + ratios lower than 1. The most prevalent comorbidities were smoking, depression, alcoholism, and herpes zoster infection, in males and females. Conclusions: The most relevant comorbidity in both genders was herpes zoster, an important marker of immunity in patients. The lowest mean was observed among patients with neurotoxoplasmosis.Keywords: HIV infection. Comorbidities. CD4 + /CD8 + ratio. Patients with HIV may have several comorbidities that could contribute to the reduction in the CD4 + /CD8 + ratio. It has been observed that long-term smoking decreases the number of CD4 + cells, and increases the number of CD8 + cells 7 .Our objective was to identify comorbidities related to HIVpositive patients treated at the sexually transmitted disease/ acquired immunodeficiency syndrome Specialized Care Of all 424 evaluated medical records that had data regarding CD4 + /CD8 + ratio, 388 patients presented values lower than 1. The analysis by sex showed 41% female and 59% male patients. The mean age of these patients was 35.54 (± 11.01) years, and the average age among HIV-positive men and women was 36.59 and 34.23 years, respectively. Of the 388 included patients, 243 (62.6%) were using specific antiretroviral drugs for HIV infection, highly active antiretroviral therapy (HAART), while 145 (37.4%) had never been on antiretroviral therapy (n = 113) or did not adhere to treatment (n = 32).