We described a patient who developed heart failure and pericarditis after bone marrow transplantation for a hematologic malignancy. The patient died of heart failure complicated by pneumonia. Despite extensive surveillance, an infectious cause for the heart failure was not found while he was alive. In addition, cultures of specimens obtained at autopsy did not reveal a cause for the heart failure. Enterovirus was detected by the polymerase chain reaction (PCR) in two samples of pleural fluid that were obtained 21 days apart while he was alive. After the patient died, enteroviral RNA was also detected in his lungs, liver, and spleen, indicating a generalized infection. Analysis of the PCR products revealed sequences sharing close homology with the coxsackie B-like group of enteroviruses. In addition to reporting this case, we review the literature regarding enteroviral infections after transplantation.