Molecularly imprinting technique was combined with magnetic nanoparticles to synthesize molecularly imprinted polymer-encapsulated particles for selective removal and efficient separation of estrogenic compounds from water. The core-shell-structured particles were successfully prepared by a novel 2-h ultrasonication-assisted synthesis in a mixture of water and organic solvent using dual-layer surfactant-modified magnetic particles as core, the most physiologically active estrogenic compound (17 beta-estradiol) as template, and widely adapted methacrylic acid as functional monomer. Ultravioletvisible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and magnetic separation were used to characterize the particles. High-performance liquid chromatographytandem mass spectrometry was used for quantitative binding performance analysis at low-nanogram per milliliter levels. The particles exhibited satisfactory recognition of 17 beta-estradiol in water. They possessed great potential for rapid, cost-effective, and efficient separation of estrogenic compounds from aqueous environment with specificity. POLYM. ENG. SCI., 2012. (C) 2012 Society of Plastics Engineers