To investigate the relationship of As(2)O(3)-induced leukemic cell apoptosis with NF-kappaB activation and expression of VEGF, MMP9, apoptosis of K562-n cells induced by As(2)O(3) was analyzed by Annexin V, the dynamic changes of NF-kappaB, MMP9 and VEGF expressions were detected by immunohistochemistry. The results showed that activity of NF-kappaB could be increased, accompanied by higher level of expression of MMP9 and VEGF when apoptosis of K562-n cells was induced by As(2)O(3). Dexamethasome not only increased significantly the apoptotic rate, but also suppressed the activation of NF-kappaB of K562-n cells induced by As(2)O(3). Furthermore, there was a positive correlation between the expression of MMP9, VEGF and the activity of NF-kappaB. It is concluded that As(2)O(3) can induce apoptosis, in the meanwhile, activate NF-kappaB and up-regulate expression of MMP9 and VEGF in K562-n cell line. The mechanism of apoptosis of K562-n cells enhanced by dexamethasome may be related to suppression of the activation of NF-kappaB and expression of MMP9 and VEGF.