Background: The purpose of this study is to estimate the survival rates of AIDS patients diagnosed in the state of Rio Grande do Sul, Brazil, between 2003 and 2007, and followed up until 2014. Methodology/Principal Findings: A retrospective, analytical cohort study was conducted based on secondary data, obtained from official information systems. 12,610 patients were studied. Patients’ survival rates were analyzed using Kaplan-Meier limit estimator. The survival time of AIDS patients was defined as the interval, in months, between the date of diagnosis and the date of death or censoring. The observed probability of survival was 67.35% +-0.42. According to the results of the Cox proportional hazards model, the following factors showed association with the evolution of AIDS, regardless of other exposures: HAART 1 (HR= 3.7 CI 95% 1.9–7.1); no treatment (HR=6.4 CI 95% 3.2–12.5); race/color of patients classified as black (HR=1,5 CI 95% 1.3–1.8); race/color of patients classified as brown (HR=1.3 CI 95% 1.1–1.6); IDU exposure category (HR=1.5 CI 95% 1.2–1.9); having up to 8 years of schooling (HR=1.7 CI 95% 1.4–1.9); having no schooling (HR=2.1 CI 95% 1.5–3.1); first CD4+ count below 200 cells/mm3 (HR=3.3 CI 95% 2.5–4.4) or between 200–349 cells/mm3 (HR=1.9 CI 95% 1.4–2.5); and viral load >500 cells/mm3 (HR=1.6 CI 95% 1.3–2.0). Conclusions: The survival rate of AIDS patients, diagnosed in the state of Rio Grande do Sul between 2003 and 2007, is 67.35% over a 12-year follow-up period. Inequity-related issues may be addressed by the state to improve survival time among less privileged populations affected by the disease.