The aim of this study was to investigate the potential benefit of combination therapy with magnetic nanoparticle of Fe(3)O(4) and 5-Bromotetrandrine (5-BrTet) on chronic leukemia. The apoptosis was detected by flow cytometry (FCM), Wright staining and light microscope; the expressions of BAX and BCL-2 were measured by Western blot. The results showed that combination of daunorubicin (DNR) with either MNP (Fe(3)O(4)) or 5-BrTet exerted a potent cytotoxic effect on K562/A02 cells, while MNP (Fe(3)O(4)) and 5-BrTet co-treatment could synergistically enhance DNR-induced apoptosis. After treated with this regimen, the typical apoptotic morphological features were found in K562/A02 cells; the expression level of BCL-2 decreased and BAX increased markedly. It is concluded that MNP (Fe(3)O(4)) or 5-BrTet with DNR can induce apoptosis in K562/A02 cells, and they show distinct synergism when used together. The down-regulation of BCL-2 and the up-regulation of BAX may play important roles.