Lymphoproliferative disease virus, a type-C retrovirus, is the etiologic agent of a naturally acquired lymphoproliferative disorder in turkeys. The disease is characterized by rapid induction of lymphoproliferative lesions with morphologic and histopathologic features resembling those of reticuloendotheliosis. Owing to lack of overt clinical manifestations, early detection of lymphoproliferative disease virus is essential for preventing the rapid horizontal spread of the disease that can decimate flocks. We describe development of a simple, rapid, sensitive, and highly specific assay, using the polymerase chain reaction, capable of providing differential diagnosis of the disease soon after infection.