We investigated the efficacy of arsenic trioxide (ATO) in patients with refractory severe aplastic anemia (SAA). A total of 5 consecutive adults were enrolled. The patients received ATO at a dose of 0.15 mg/kg intravenously daily for 5 days every week for 8 weeks. If necessary, a second course was performed after an interval of one week. All patients achieved clinically significant responses to ATO. The overall complete response rate and overall response rate at 17 weeks were 60% (3/5) and 100%(5/5), respectively. So treatment with ATO may be a feasible approach in patients with refractory SAA.