In the present study, drug carrying magnetic nanocomposite spheres were fabricated using oil-in-oil emulsion/solvent evaporation method and characterized via different techniques. The spheres with a diameter of 200 nm and 3 mu m consist of poly (lactic-co-glycolic acid) (PLGA), a drug and magnetic nanoparticles (e.g., Fe3O4 or Co0.5Zn0.5Fe2O4). The spheres were initially dispersed in both deionized (DI) water and viscous glycerol solutions, and pumped in a magnetic field at different tube diameters, pump speeds and concentrations to study the hydrodynamic behavior of drug-carrying magnetic nanocomposite spheres. The test results showed that the magnetic field, tube diameter, pump speed and magnetic nanoparticle concentrations in the spheres drastically changed the capturing efficiency of the spheres. In the in vivo tests of the spheres, these parameters should be considered in order to increase the efficiency of the drug delivery systems.