Large granular lymphocytic (LGL) leukaemia is an uncommon clonal lymphoproliferative disorder. The WHO classification recognizes three distinct disorders of LGLs: T-cell large granular lymphocytic leukaemia (T-LGL), chronic lymphoproliferative disorders of NK-cells (CLPD-NK) and aggressive NK-cell leukaemia. Despite the different origin of cells, there is considerable overlap between T-LGL and CLPD-NK in terms of clinical presentation and treatment. Majority of these patients are asymptomatic and may not need treatment. When significant cytopenias occur, the application of immunosuppressive therapy often should be considered. In contrast, aggressive NK cell leukemia and the rare CD56(+) aggressive T-LGL leukemia have a fulminant clinical course and an earlier age of onset, therefore, more intensive combination chemotherapy is required, followed by allogeneic hematopoietic stem cell transplantation. However, these diseases are relatively rare, there are few clinical trials to guide management. In this review, the pathogenesis, diagnosis, treatment and prognosis of this leukemia are summarized and discussed.