The reactive hemophagocytic syndrome is a rare clinical-pathological entity which usually has a benign evolution and which is characterized by the systemic proliferation of mature histiocytes, with a great phagocytosis ability and which occurs in a secondary form in some infections and neoplasias and after the administration of certain drugs. We present a case of reactive hemophagocytic syndrome in a patient presenting a non-Hodgkin lymphoma, of crest malignancy, B immunoblastic and kappa monoclonal, with fatal evolution and in which the diagnosis was obtained after necropsy.