In this paper, fluorescent-magnetic Fe3O4@LaF3:Ce,Tb nanocomposites were synthesized by combining fluorescent LaF3: Ce, Tb and magnetic Fe3O4 nanoparticles into new 'two-in-one' entities. The obtained Fe3O4@ LaF3: Ce, Tb nanocomposites were small (about 30 nm in diameter) and well dispersed in water. Under ultraviolet light irradiation, the Fe3O4@ LaF3: Ce,Tb nanocomposites emitted bright green fluorescence, and they could be easily manipulated by an external magnetic field. Such bifunctional nanocomposites may find many biomedical applications, such as cancer detection and drug delivery. And the method we used can be extended to the synthesis of other nanocomposites based on lanthanide-doped materials and metal oxides. (C) 2008 Elsevier B. V. All rights reserved.