Intravascular lymphoma is an uncommon and often overlooked form of non-Hodgkin's lymphoma characterized by extensive proliferation of lymphoid cells within the lumina of small and medium-sized vessels. Clinical symptoms of the disease are variable and often nonspecific, mostly neurologic in nature. With an aggressive course, intravascular lymphomatosis has a poor prognosis and is rarely diagnosed ante mortem. We describe here a 76-year-old woman with the clinical diagnoses of hemolytic anemia and progressive lethargy where intravascular lymphomatosis turned out as the underlying cause of the disease.