This study was purposed to explore the caspase-independent apoptosis pathway in human multiple myeloma cell RPMI8226 induced by arsenic trioxide (As(2)O(3)). MTT method was used to analyze the proliferation inhibition rate; flow cytometry was used to detect the apoptosis rate; Western blot was used to determine the expressions of BCL-2 and Caspase-3 in RPMI8226 cells. The results showed that As(2)O(3) (0.1 - 20 µmol/L) significantly inhibited the proliferation of RPMI8226 (P < 0.05) in concentration- and time-dependent manner. Compared with the group treated with As(2)O(3) (10 µmol/L) alone, the apoptosis rate of zVAD-fmk (20 µmol/L) and As(2)O(3) combined treated group did not change. Compared with the group treated with As(2)O(3) (10 µmol/L) alone, zVAD-fmk (20 µmol/L) combined with As(2)O(3) (10 µmol/L) treatment group showed significant increase of expressions of Caspase-3 and BCL-2. It is concluded that As(2)O(3) can inhibit the proliferation of RPMI8226 cells. As(2)O(3) can induce apoptosis of RPMI8226 cells, and a caspase-independent process probably exist in As2O3-inducing RPMI8266 cells apoptosis.