Twenty-four patients with aplastic anemia (19 severe: 5 moderate) were treated with combined immunosuppression consisting of antithymocyte globulin (ATG: Lymphoser Berna, Swiss Serum and Vaccine Institute Berne) and high-dose methylprednisolone. Danazol or meptiostane was administered concurrently for at least 3 months. Three batches of ATG were used, two were not absorbed with thrombocytes and one was absorbed with thrombocytes for the prevention of thrombocytopenia. Nine of 20 evaluable patient (45%) had sustained improvement in hematopoiesis within 3 months of treatment. Nine of 14 patients (64%) showed a response to ATG without thrombocyte absorption, on the other hand, none of 6 patients responded to ATG with thrombocyte absorption. By life table analysis, the 3 year probability of survival was 81 +/- 27% after the combined immunosuppressive therapy. These results indicated that ATG therapy was very effective in Japanese patients with aplastic anemia.