6 patients with a chronic, clinically heterogeneous proliferative disorder of the large granular lymphocytes (LGL) were investigated. In each case the majority of peripheral blood lymphocytes reacted with HNK-1, OKT3 and T11 monoclonal antibodies, whereas morphology and other immunological features varied from case to case. 2 cases were of particular interest. 1 patient had an expansion of HNK-1 stained, large agranular rather than granular lymphocytes; another patient's LGL simultaneously expressed HNK-1, OKT4 and T8 antigens. The heterogeneous features of these abnormally expanded cell populations are similar to those of the normal cell subsets from which they are likely to have originated.