To prepare Fe(3)O(4)-magnetic nanoparticles loaded with adriamycin and investigate the reversal role of drug-loaded nanoparticles in K562 and resistant cell line K562/A02, the drug-loaded nanoparticles were prepared by using mechanical absorption polymerization at different conditions of 4 degrees C or 37 degrees C for 24 or 48 hours. The survival of cells cultured with drug-loaded nanoparticles for 48 hours was detected by MTT assay, then the growth inhibition efficacy of cells was calculated. The results showed that the growth inhibition efficacy of both two cell lines was enhanced with increasing concentration of Fe(3)O(4)-magnetic nanoparticles. The inhibitory ratio of two cell lines obtained at 4 degrees C and for 48 hours was significantly better than that at 37 degrees C and 24 hours. In conclusion, Fe(3)O(4)-magnetic nanoparticles can load adriamycin by using mechanical absorption polymerization, but depended on proper temperature and time. Furthermore, drug-loaded nanoparticles showed an ability reversing multidrug resistance.