A 52-year-old female was diagnosed with relapsed APL in 2000. After obtaining informed consent, we administered 10 mg/day of arsenic trioxide intravenously. The complications were vomiting, increased transaminase and ATRA syndrome which included high fever, retention of body fluid, pleural effusion, pericardial effusion and respiratory failure from day 16. Administration of steroid and low dose chemotherapy (DNR 60 mg x day 1-2, BH-AC 250 mg x day 1-2) with arsenic was effective for APL syndrome, and complete remission (CR) was obtained at day 35 and PML-RAR mRNA became negative. After obtaining CR, consolidation chemotherapy was conducted and the patient was maintained the CR for more than 18 months. Although arsenic trioxide may be effective for relapsed APL, sufficient caution is needed because of the possibility of various complications.