Multiple myeloma (MM) characterized by proliferation of plasma cells in bone marrow and production of monoclonal immunoglobulinʹs. Recently, arsenic trioxide (ATO), has been considered for treatment refractory MM. We assessed the safety and efficacy of ATO for patients with refractory MM. A phase 2, study of arsenic trioxide was conducted in 12 MM patients, whose refractory to two standard therapy. Patients received arsenic trioxide, 0.25 mg/kg/d for 5 d/week during the first 2 consecutive weeks of each 4-week cycle with 2 week rest. Patients who completed one 4-week cycle were evaluated for response to treatment. Twelve patients with refractory multiple myeloma received ATO. Disease assessment was based the amount of serum proteins electrophoresis. Of the10 patients; stable disease was observed in four patients(33%), progression disease in five patients (41.6%), complete response in one patient (3.8%) and the remaining two patients could not be assessed for a response (because of increased liver enzymes after the first week). Some adverse events: increase liver enzymes and serum creatinine, neutropenia, pruritus, nausea, vomiting, lower extremities edema, noninfectious diarrhea was observed. These results indicate that ATO is active and well tolerated as a single-agent salvage therapy, even in patients with late-stage, refractory MM.