A 20-year-old woman presented with fever, fatigue, and weight loss. She had a history of Holt-Oram syndrome and primary EBV infection a year prior. Testing showed pancytopenia, hepatosplenomegaly, and elevated ferritin. A bone marrow biopsy showed hemophagocytosis. She was diagnosed with EBV-associated hemophagocytic syndrome and died despite treatment. Hemophagocytic syndrome is caused by impaired NK and cytotoxic T cell function leading to uncontrolled immune activation and cellular damage. It can be genetic, infection-associated, malignancy-associated, or associated with autoimmune diseases. Treatment involves controlling inflammation, the underlying trigger, and supportive care.