This paper demonstrates bovine serum albumin (A1) and ovalbumin (A2) can be used as stabilizer to prepare aqueous magnetic fluids for gene therapy. The content of magnetite depends on the reaction temperature and time. The reaction is performed at 70 degrees C for 30 min, which is appropriate to obtain stable aqueous magnetic fluids. The super paramagnetic magnetic fluids composed of Fe3O4 cores, which have average diameter about 8 nm. A high positive zeta-potential of +46.0 mV and suitable hydrodynamic diameters were realized. (c) 2007 Published by Elsevier Ltd.