We describe the case of a nonimmunocompromised middle age man, who presented with a history of fever, nausea, disturbance of consciousness, peripheral eosinophilia and a bone marrow eosinophilic hyperplasia. A persistent unexplained eosinophilia was initially interpreted as a sign of the hypereosinophilic syndrome because all known causes of secondary eosinophilia had been excluded and there were evidence of multiorgan dysfunction. A cervical lymph node biopsy was remarkable for malignant T cell lymphoma according to the hypothesis that patients with the hypereosinophilic syndrome should be carefully examined for an underlying proliferation of clonal T cells. The patient died of CID after 3 months of hospitalization. At autopsy he was found to have a generalized CMV infection.