Pneumocystis Pneumonia (PCP) is caused by the fungus Pneumocystis jirovecii. PCP is also a common opportunistic infection among people living with the human immunodeficiency virus (HIV) and those receiving immune-suppressive therapy. In recent years, advances in antiretroviral therapy have led to improved immune function in patients with HIV. This study's objective was to assess temporal trends in PCP epidemiology among hospitalized patients with HIV/AIDS in the US and comparing data for hospitalizations with HIV with PCP to those without PCP. METHODS: The national inpatient sample (NIS) data were analyzed from 2002-2014. The discharge coding identified hospitalized patients with HIV or AIDS (ICD-9 code 042x, 043x, 044x, 079.53, 795.71, V08, V65.44, 042.9) with or without PCP (ICD-9 code 136.3). Prevalence, length of stay (LOS), and inhospital mortality were assessed using multivariate regression analysis. The study analysis was done using IBM SPSS software. RESULTS: We identified 3,011,725 hospitalizations with HIV/AIDS during the study period (mean patient age 45±11 years; 65% were male; 24.8% were White; 47.4% were Black, and 12.3% were Hispanic). Almost 70% of the hospitalizations were in an urban teaching setting. PCP was present in 5% of the patients with a diagnosis of HIV. Among HIV hospitalizations with PCP and without PCP, there were only slight differences in the race, but the males had a higher prevalence than females (70% vs. 30%). Among all HIV admissions, rates of PCP progressively declined from 6.7% in 2002 to 3.5 % in 2014 (p < 0.001). Overall mortality in patients with HIV was 3.3% and was significantly higher in those with PCP than without PCP (9.9% vs. 2.9%; P< 0.001). After adjusting for demographics and other comorbidities, PCP has higher odds of hospital mortality 3.082 (OR 3.082; 95% CI, 3.007 to 3.159; P< 0.001). Among the other comorbidities, congestive heart failure, coagulopathy, lymphoma, metastatic cancer, and weight loss tend to have higher mortality rates among HIV patients. CONCLUSIONS: From 2002 to 2014, the rate of PCP in HIV patients has decreased significantly in the United States but is associated with substantially higher mortality. Early recognition of declining immune status, prompt investigation, and antibiotic therapy are essential in managing PCP in this population.