Surface antigens of T lymphocytes in peripheral blood mononuclear cells from 19 patients with systemic lupus erythematosus (SLE), 14 patients with Sjögren's syndrome (SS), and 14 healthy control subjects were studied by 2-color analysis. The proportion of CD4+2H4+ cells, which correspond to a suppressor/inducer subset, was decreased significantly in both SLE and SS. In contrast, the percentage of CD4+4B4+ cells, which define a helper/inducer subset, showed no significant difference among the patient groups. These data suggest that quantitative defect of suppressor/inducer cells may play an important role in the immunoregulatory disturbance in SLE and SS.