Hemophagocytic syndrome (HPS) is a rare life-threatening condition caused by massive cytokine release from activated macrophages and lymphocytes. The paper depicts the development of HPS in different infections, malignancies, and autoimmune diseases. It describes a clinical case of hemophagocytic syndrome in a 63-year-old female patient with adult-onset Still’s disease and high fever accompanied by neutrophil leukocytosis and a drastic left leukocyte count shift, high procalcitonin levels, hepatosplenomegaly, edematous syndrome, and progressive multiple organ dysfunction with the development of disseminated intravascular coagulation and adult respiratory distress syndrome. The diagnosis of HPS was established according to the diagnostic criteria and verified by autopsy: phagocytes in liver and lung tissues.