Background: Hemophagocytic lymphohistiocytosis (HLH) is an aggressive and life-threatening syndrome of excessive immune activation Aim: To describe the clinical characteristics, causes and survival associated with HLH. Material and Methods: Review of medical records of patients with HLH attended between 2004 and 2016. They were classified according to their probable cause in: associated with immunosuppression, cancer, post-infectious or idiopathic. Kaplan-Meier survival analysis was performed. Results: Twenty seven patients with HLH aged 18 to 87 years (59% men), were detected. Fourteen (52%) were secondary to immunosuppression, six (22%) were post-infectious, five (18%) were associated with cancer and two (7%) were of unknown cause. There were no significant differences in clinical or laboratory features between these etiologies. Within the immunosuppressed group, 12 (86%) were patients with oncologic or hematologic diseases or bone marrow transplantation. Associated cancers were mostly oncohematologic diseases. Thirty-day mortality was 53.4% (95% confidence intervals (CI) 32.7-70.3%), despite the treatment. Mortality was significantly associated with the presence of renal failure with a hazard ratio (HR) of 3.4 (95% CI of 1.2-9.9, p =0.025). Treatment of the underlying disease proved to be protective against mortality with an HR of 0.3 (95% CI 0.1 to 0.98, p = 0.046). Conclusions: The prognosis of HLH could be related to the treatment of the underlying disease. The study of the pathophysiology of this syndrome will allow a better understanding and treatment.