Superparamagnetic polymer nanofibers intended for drug delivery and therapy are considered here. Magnetite (Fe(3)O(4)) nonoparticles in the diameter range of 5-10nm were synthesized in aqueous solution. Polymer nanofibers containing magnetite nonoparticles were prepared from commercially available poly(hydroxyethyl methacrylate), PHEMA, and poly-L-lactide (PLLA) by the electrospinning technique. Nanofibers with diameters ranging from 50 to 300 nm were obtained. Nanofibers containing up to 35 wt% magnetite nanoparticles displayed super-paramagnetism at room temperature. The blocking temperature was about 50 K for an applied field of 500 Oe, and the saturation magnetization was 3.5 emu g(-1) and 1.1 emu g(-1) for Fe(3)O(4)/PHEMA and Fe(3)O(4)/PLLA nonofibers, respectively, and depended on the amount of Fe(3)O(4) nanoparticles in the nanocomposites. To test such magnetic nano-objects for applications as drug carriers and drug-release systems we incorporated a fluorescent albumin with dog fluorescein isothiocyanate (ADFI).