ABSTRACT Introduction: Hemophagocytic lymphohistiocytosis comprises a systemic hyperactivation of macrophages that requires prompt recognition of symptoms and early treatment. Objective and Method: In this context, we described clinical and laboratory characteristics, therapeutic modality and outcome of 21 patients with HLH treated at a pediatric oncology hospital between January 2000 and February 2019. Results: HLH mainly affected females, fever was the most frequent clinical sign and hyperferritinemia was the most prevalent laboratory abnormality. All patients were admitted to the intensive care unit (ICU) at some point. Fifteen (71.4%) patients presented resolution criteria and eight (53.3%) of them presented reactivation. The mortality rate was 57.1% and the mean time between diagnosis and death was 9.98 months. The 5-year overall survival (OS) was 36.7%. We observed a significant difference in prognosis associated with reactivation of HLH. These patients demonstrated an estimated 5-year OS of 25%, while all patients that did not reactivate were alive until the end of the follow-up. Conclusion: In conclusion, HLH is a rare disease with a high mortality rate, especially in patients with disease reactivation and those with familial- or immunodeficiency-associated forms, which makes early recognition and genetic testing crucial for appropriate management and prompt SCT indication.