Malignancy-associated hemophagocytic lymphohistiocytosis (mal-HLH) is a severe hyperinflammatory syndrome with poor prognosis. We evaluated mal-HLH in Sweden with regard to population-based incidence, clinical features, and survival. Using the Swedish Patient Registry for 1997-2018, we identified 307 adults (≥18-years) and 9 children (209 males, 107 females; p<0.001), with both an HLH-related diagnosis and malignant disease according to ICD-10, corresponding to 0.19/100,000 …