Granular lymphocytes proliferative disease(GLPD) is a heterogeneous disorder and the pathogenesis is likely to be complex. More recently, however, it has become obvious that about one third of GLPD belongs to NK-lineage and nearly one half of the NK-GLPD contains EBV-DNA. In addition, lethal midline granuloma(a subtype of nasal lymphoma) is also classified as NK/T-lineage and exclusively contains EBV-DNA. These NK-GLPD likely represent fever, splenomegaly and extranodal involvement, such as skin, lung and G-I tract. Although some elderly patients show a chronic clinical course, most of the patients present with an aggressive course and sometimes hemophagocytic syndrome is observed in the clinical course.