Conclusions Polyelectrolyte coated magnetically responsive nanocap-sules were successfully synthesized by direct encapsulation ofnanoemulsion droplets containing hydrophobic Fe3O4nanopar-ticles in the polymer multilayer shell prepared using the layerby layer (LbL) technique. Various sizes of hydrophobic magneticnanoparticles (5, 10 and 20 nm) were used for the preparation. Theaverage size of synthesized nanocapsules was around 100 nm. Forthe purpose of biomedical application the nanacapsules shells werepegylated that was evidenced by zeta potential measurements.They maintain colloidal stability for the period not shorter than 30days. In this paper and our previous study [26], we demonstratedthat magnetic nanoparticlesparticles can be easily incorporatedinto either core or shell of nanocapsules of the size of c.a. 100 nm.Thus, our magnetically responsive nanocapsules may contributeto the further development of new strategies for targeted drugdelivery systems. The optimal localization of magnetic nanoparti-cles depends on their nature (hydrophobic or hydrophilic) and onparticular application. In our opinion the magnetic properties ofthe carriers are less vulnerable to the effect of environment if ironoxide nanoparticles are located in the nanocapsule’s core. On theother hand encapsulation of magnetic nanoparticles in the shellcan produce higher loading, thus, higher susceptibility to magneticfield.