This report describes a patient with severe unexplained recurrent hemolytic anemia and congestive heart failure. Donath-Landsteiner antibodies, suggestive of paroxysmal cold hemoglobinuria (PCH), were detected. On postmortem examination, a diagnosis of non-Hodgkin's lymphoma, primarily involving the heart, was made. This previously undescribed association expands on the clinical and serologic spectrum of non-Hodgkin's lymphoma and PCH. Unexplained hemolytic anemia in the elderly should raise the suspicion of an underlying lymphoproliferative disorder.