We prepared the nano-sized magnetic fluid in aqueous phase solution to modify the killed yeast cells (Saccharomyces cerevisiae). Subsequently, the yeast cells with good magnetic response was obtained.The infrared spectroscopy analysis showed that the modified yeast cells increased obviously the absorption at the Fe-O characteristic peak of 581 cm(-1). Moreover, the transmission electron microscopy picture indicated the magnetic nanoparticles presented individually or aggregately on the yeast cell surface. Under the experimental conditions, the magnetically labeled yeast with 160 microL showed the adsorption percentage up to 100% in 1 mL direct scarlet dye solution with the concentration of 0.4 mg/mL, and arrived at the adsorption equilibrium within 8 min. Besides, the adsorbed dyes can be eluted in 70% alcohol with a desorption percentage of 99.18%. Because of the strong adsorption capacity, the high adsorption speed and easy of magnetic separation, the magnetically modified yeast cells are the promising biosorbent candidates for removal of water-soluble dyes.