Background: Severe hypoxemic respiratory failure (SHRF) due to Pneumocystis jiroveci pneumonia (PJP) in AIDS patients represents the main cause of admission and mortality in respiratory intensive care units (RICUs) in low-and middle-income countries. Objective: The objective of this study was to develop a predictive scoring system to estimate the risk of mortality in HIV/ AIDS patients with PJP and SHRF. Methods: We analyzed data of patients admitted to the RICU between January 2013 and January 2018 with a diagnosis of HIV infection and PJP. Multivariate logistic regression and Kaplan-Meier method were used in data analysis. The RICU and inhospital mortality were 25% and 26%, respectively. Multivariate analysis identified four independent predictors: body mass index, albumin, time to ICU admission, and days of vasopressor support. A predictive scoring system was derived and validated internally. The discrimination was 0.869 (95% confidence interval: 0.821-0.917) and calibration intercept (α) and slope (β) were 0.03 and 0.99, respectively. The sensitivity was 47.2%, specificity was 84.6%, positive predictive value was 89.2%, and negative predictive value was 82.6%. Conclusions: This scoring system is a potentially useful tool to assist clinicians, in low-and medium-income countries, in estimating the RICU and inhospital mortality risk in patients with HIV/ AIDS and SHRF caused by PJP.