Abstract: Background: Pneumocystis pneumonia (PCP) incidence in acute myeloid leukemia (AML) patients have not been well described and some studies have shown the risk of this infection in these groups of patients. In this systematic review, we reviewed the published studies about PCP in AML to evaluate the PCP incidence and outcomes in these patients and then focuses on its immunological mechanism. Method: All articles reviewed in this collection are from recruited sites: PubMed and Embase databases. No time limit was considered for article searching. The following keywords were used: (“Pneumonia, Pneumocystis” OR Pneumocystis Pneumonia” OR “Pneumocystis jirovecii”), AND (“leukemia, myeloid, acute OR acute myeloid leukemia”). Our search strategy yielded 356 articles. After implementing the exclusion and inclusion criteria, the final papers were selected and reviewed. Result: By our search, 356 articles were found (316 in PubMed and 40 in Embase). After the implementation of inclusion and exclusion criteria, seven papers remained. A total of seven articles with a total number of 41 patients were included. Conclusion: Affected patients appear to have a clear resistance to PCP infection despite chemotherapy and bone marrow suppression due to the preservation of a specific immunological milieu in the lung. In fact, may be due to immunological stability of the lungs that remains intact. Further studies are needed.