Three kinds of magnetic nanoparticle, tetraheptylammonium capped nanoparticles of Fe(3)O(4), Fe(2)O(3) and Ni have been synthesized, and the synergistic effect of these nanoparticles on the drug accumulation of the anticancer drug daunorubicin in leukaemia cells has been explored. Our observations indicate that the enhancement effect of Fe(3)O(4) nanoparticles is much stronger than that of Fe(2)O(3) and Ni nanoparticles, suggesting that nanoparticle surface chemistry and size as well as the unique properties of the magnetic nanoparticles themselves may contribute to the synergistic enhanced effect of the drug uptake of targeted cancer cells.