Objective:To improve the understanding of adult primary hemophagocytic syndrome (HPS) with aggressive natural killer cell leukemia (ANKL).Methods:The clinicopathological data of one adult patient with suspected primary HPS complicated with ANKL in Huiqiao Medical Center, Nanfang Hospital of Southern Medical University in October 2017 were retrospectively analyzed, and literatures were reviewed.Results:A 21-year-old male patient presented with persistent fever, hemocytopenia, splenomegaly, low fibrinogen, a significant increase in ferritin, hemophagocytes in bone marrow, decreased natural killer (NK) cell activity, and increased soluble CD25. Flow cytometry detection showed that the expression of NK cells was abnormal, and there were familial lysosomal trafficking regulator (LYST) and UNC13D gene defects. He was suspected of primary HPS complicated with ANKL. The patient was given 4 courses of EPOCH+PEG-Asp (etoposide, dexamethasone, vindesine, cyclophosphamide, doxorubicin hydrochloride liposome, pegaspargase) regimen chemotherapy, 20 mg of citalopidine twice a week maintenance therapy and matched unrelated hematopoietic stem cell transplantation. After 35 months of follow-up, he got sustained remission.Conclusions:Even if there are secondary causes of adult HPS, it is necessary to screen out related genes to avoid misdiagnosis. HPS patients with ANKL progress rapidly, and the early mortality is high. EPOCH+ PEG-Asp regimen induction therapy and allogeneic hematopoietic stem cell transplantation should be used as early as possible after diagnosis.