Ninety patients were grouped according to three different forms of acquired immune deficiency syndrome (AIDS): Kaposi's sarcoma "recent outbreak" type (38), reactive lymphadenopathy (27), and opportunistic infections (17), and a fourth group of patients with "classic" Kaposi's sarcoma (8). All patients with "classic" Kaposi's sarcoma were previously treated with electron-beam irradiation. These four groups were compared with 40 normal control subjects. Peripheral blood mononuclear cells isolated by density separation were reacted with a panel of mouse monoclonal antibodies that recognizes all peripheral blood T cells (OKT3-positive), helper (OKT4-positive), and suppressor (OKT8-positive) T cell subsets. The OKT4/OKT8 ratio was used to define the balance between these two subsets. All three groups with AIDS with or without Kaposi's sarcoma showed a decrease in the OKT4/OKT8 ratio. The group with "classic" Kaposi's sarcoma showed individual T cell subset values that were also abnormal. These findings confirm the previously reported imbalance of T cell subsets in patients with AIDS and Kaposi's sarcoma, which is also evident in patients with treated "classic" Kaposi's sarcoma.