The aim of this retrospective study was to analyze the characteristics of PCP patients in both groups, and to identify clinical factors that contributed to survival. PCP remains a leading opportunistic infection in HIV infected patients, and the number of PCP cases in those receiving immunosuppressive drugs has increased. However, epidemiological data on PCP are lacking in mainland China. Moreover, there are limited explicit data about whether there are large differences in mortality, the characteristics between the two populations, and clinical factors that contribute to the survival in China. This investigation is a 5-year, retrospective study of 151 definite cases of PCP admitted to two tertiary medical centers. The main risk factors for PCP are deficiencies in cellular immunity and the use of immunosuppressive agents. Similar to previous reports, our patients developed PCP even following the use of glucocorticoids in a low dose or for a short duration. This is consistent with other studies which indicate that a proportion of non-HIV infected patients developed PCP when receiving glucocorticoids as tapering dosage, and most of these cases had lymphopenia. There are guidelines for prophylaxis against PCP for patients with hematological diseases, solid tumors, and recipients of hematopoietic stem cell transplantation and solid organ transplantation. For NH-PCP patients with other underlying diseases, there is no consensus approach to patient selection for PCP prophylaxis and duration of prophylaxis. Chemoprophylaxis for HIV-PCP is not initiated until there is a measured decline in the peripheral CD4 counts,200 cells/ml. Data suggest that low peripheral blood CD4 counts may also help identify immunocompromised patients at risk for NH-PCP. However, the role of the peripheral CD4 counts in predicting PCP in this population remains to be defined. In our study, CD4 counts for 59% of non-HIV cases were,300 cells/ml, and 63% were, 400 cells/ml. However, this number approaches CD4 counts for healthy individuals. Despite the underlying risk factors associated with immunosuppressive agents, 97.8% of NH-PCP patients receiving immunosuppressive therapy in our study were not receiving PCP primary prophylaxis before admission.