PATIENT CHARACTERISTICS: Age: 15 to 55 Performance status: Aplastic anemia patients: Karnofsky 80-100% Graft failure patients: Karnofsky 20-100% Life expectancy: Not specified Hematopoietic: See Disease Characteristics Hepatic: Aplastic anemia patients: Bilirubin no greater than 2.0 mg/dL SGOT/SGPT no greater than 3 times normal PT/PTT normal (except when aplastic anemia secondary to viral hepatitis) Graft failure patients: Mild to severe venoocclusive disease allowed Renal: Aplastic anemia patients: Creatinine no greater than 2.0 mg/dL Creatinine clearance at least 60 mL/min Cardiovascular: Aplastic anemia patients: Left ventricular ejection fraction at least 45% by MUGA or echocardiography No myocardial infarction within the past 6 months No uncontrolled arrhythmias Pulmonary: Aplastic anemia patients: FEV1 and DLCO at least 50% predicted Other: Aplastic anemia patients: No uncontrolled diabetes mellitus or thyroid disease No active serious infections HIV negative Not pregnant or nursing Negative pregnancy test No psychosocial problem that would preclude study compliance