Hemophagocytic lymphohistiocytosis (HLH) is a rare, potentially fatal, severe condition of hyperinflammation caused by the uncontrolled proliferation of activated lymphocytes and histiocytes secreting high amounts of inflammatory cytokines. Here we report a fatal hemophagocytic syndrome in a 11-year-old boy with a diagnosis of both Crohn's disease receiving immunosuppressive therapy and familial Mediterrenean fever. It is important to evaluate the patients with inflammatory bowel disease receiving immunosuppressive therapy presenting with unexplained fever, cytopenia, progression of organomegaly and biochemical changes for the investigation of HLH for diagnosis and treatment. (C) 2009 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.