HLH describes a clinical of syndrome hyperinflammation resulting in an uncontrolled and ineffective immune response. Hypercytokinemia level cause severe disorders, high mortality rate. Objectives: To study clinical characteristics, investigation and outcome of patient with HLH in National Hospital of Pediatrics. Methods: A descriptive cross sectional study in 53 children were diagnosed HLH (Henter 2004) in National Hospital of Pediatrics from 8/2010 to 7/2011. Results: 84.9 percent cases onset disease under 2 years, clinical of HLH are variety and unspecific. Investigations: cytopenia (at least 2 of 3 lineages in the peripheral blood) 71.7 percent, hypertriglyceridemia (81.1 percent), ferritin or = 500 ug/L (96.2 percent), hemophagocytosis in bone marrow (61.4 percent), EBV infection (75.5 percent). Multiple organ dysfunction rate is high (52.8 percent). At the end of 8 weeks initial treatment: Mortality (58.5 percent), resolved (15.1 percent), continuation therapy (26.4 percent). Conclusion: Mortality in HLH is high. HLH need to be diagnosed soon and treated properly. The research need to pay attention to severe prognostic factors.