Severe aplastic anemia was diagnosed in a 58-year-old female because of pancytopenia with leukocyte count 700/microliters, hemoglobin 3.4 g/dl, platelet count 4.2 x 10(4)/microliters and fatty hypoplastic bone marrow in August 1992. In January 1993, she was admitted with an abdominal skin infection caused by pseudomonas aeruginosa. After treatment of the infection, antilymphocyte globulin was given at a dose of 2,000 mg/day for four consecutive days in July 1993. This resulted in a gradual but steady improvement in her hematological data. In February 1995, her leukocyte count increased to 2,000/microliters, hemoglobin to 15.2 g/dl and platelet count to 11.0 x 10(4)/microliters. Although no splenomegaly or myelofibrosis was found previously, from April 1993, the spleen enlarged and was palpable 10 cm below the costal margin. Her bone marrow biopsy in June 1993 revealed prominent myelofibrosis. Thereafter no changes were found in these features. Splenomegaly and myelofibrosis are characteristic of primary myelofibrosis and although the relationship is uncertain, there is no previous report on aplastic anemia with splenomegaly and myelofibrosis.