To investigate the clinical features of adult patients with hemophagocytic lymphohistiocytosis (HLH) and to explore possible risk factors for death, we retrospectively reviewed the medical records of 103 adult HLH patients hospitalized from 1997 to 2012. We analyzed the underlying diseases, clinical characteristics, 1aboratory findings, outcomes, and prognostic factors. The most common cause of HLH was hematologic malignancies (n = 49), followed by infectious diseases (n = 24) and autoimmune disorders (n = 14); 24 cases were of unknown etiology. Eight patients had a combination of underlying diseases. HLH was clinically characterized by high fever (96.1%), splenomegaly (79.6%), hepatomegaly (65.0%), lymphadenopathy (53.4%), proteinuria (31.1%), skin rash (25.2%), gastrointestinal hemorrhage (14.6%), disseminated intravascular coagulation (13.6%), increased creatinine (7.8%), and central nervous system involvement (12.6%) including altered mental status (9.7%) and cranial hemorrhage (2.9%). Laboratory abnormalities included cytopenia (99.0%), serum ferritin >500 ug/L (98.4%), liver dysfunction (98.1%), hypertriglyceridemia (88.5%), hemophagocytosis in bone marrow smear (87.4%), and hypofibrinogenemia (60.9%).In addition to the treatment they received for the underlying causes, patients received therapy for HLH consisting of corticosteroids, immunosuppressive drugs, and intravenous immunoglobulin. Twenty-six patients (25.2%) recovered after treatment, and 19 of them achieved long-term remission during follow-up. Seventy-seven patients (74.8%) died because of tumor, sepsis, multiple organ failure, or HLH-related organ hemorrhage and coagulopathy. The deceased patients were more likely to be older at disease onset, male, and to present with splenomegaly and thrombocytopenia, compared to the survivors. Treatment for the underlying diseases combined with corticosteroids, immunosuppressive agents, and immunoglobulin therapy may improve the prognosis of HLH. More attention should be paid to high-risk patients to prevent the development of serious complications associated with HLH.