Doxorubicin (DOX) loaded folate-coated magnetic Fe3O4 nanoparticles (MNPs) were prepared by co-precipitation and emulsification cross-linking method and uniform NPs with an average particle size of 15 (bare) and 35 nm (FA-MNPs), with high encapsulation efficiencies (EE), were obtained. The release profiles of conjugated DOX showed that pH 6.0 provided suitable conditions for proper drug release. IC50 analysis of C30 and CP70 cell lines after 96 h (4 days) exposure to DOX-FA-MNPs showed that the most significant IC50 were at 5.4 ± 0.6 and 11.2 ± 2.7 mM DOX loaded onto the FA-MNPs. Thus CP70 cells are more resistant to lower concentrations of drug compared to C30 cells (P < 0.05). C30 and CP70 cells reached 91 and 81.8% apoptosis after administration of DOX-FA-MNPs (5 mg/mL) compared to 49.2 and 46.6% after administration of the free drug, respectively (P < 0.05). this study indicates that FA modified MNPs enhances the DOX-induced apoptosis in both of the human ovarian cancer cell lines with sharp decreases in the levels of bcl-2 and surviving, and increased expression of caspase-3.