Magnetic poly(2-hydroxyethyl methacrylate-co-N-methacryloyl- L-phenyl alanine), p(HEMA-co-MAPA) nanoparticles were produced by emulsion polymerization technique. The nanoparticles were characterized by zetasizer, atomic force microscopy (AFM), transmission electron microscopy (TEM), electron spin resonance spectroscopy (ESR), and Fourier transformed infrared spectroscopy (FTIR) techniques. Experimental conditions were optimized for DNA adsorption in aqueous media. The effects of several factors (i. e., temperature, pH, equilibrium concentration of DNA, salt type, and ionic strength) on adsorption capacity were examined in batch studies. The maximum DNA adsorption capacity was 211.3 mg/g for nanoparticles consisting of magnetite. The adsorption isotherms and kinetics were also examined. The Langmuir model and pseudo second-order kinetics are the best fitted to the data. Following the ten adsorption-desorption cycles, the decrease in adsorption capacity was only 12%. Finally, plasmid DNA was purified from E. coli lysate by magnetite nanoparticles consisting of MAPA. The purity and molecular mass of purified plasmid DNA were determined by the use of agarose gel electrophoresis resulting in 7000 base pairs for molecular mass and OC pDNA form following elution.