We first demonstrate that As2O3 acts directly on MM cells at low concentrations of 0.5 μM∼2.5 μM, inhibiting the proliferation of myeloma cells at time- and dose-dependent fashion, and As2O3 induced apoptosis in MM cells, as evidenced by an increase in the annexin V-positive and PI negative apoptotic cell population. This evidence concerns the gene ANXA5 and plasma cell myeloma.