A novel functional complex with the thermosensitive, magnetic, and fluorescent properties of poly(N-isopropylacrylamide)-grafted poly(N-isopropylacrylamide-co-styrene) (PNNS) microspheres and Tb(III), PNNS-Tb(III), has been synthesized and characterized with different techniques. When PNNS with a core-shell structure interacts with Tb(III), Tb(III) mainly bonds to oxygen of the carbonyl groups of PNNS, forming the novel PNNS-Tb(III) complex. PNNS shows antiferromagnetic behavior, whereas the PNNS-Tb(III) complex exhibits paramagnetic behavior. The saturation magnetization is approximately 50 times higher than that of PNNS. The fluorescence intensity of the PNNS-Tb(III)complex at 545 nm is enhanced as much as 223 times in comparison with that of pure Tb(III). The novel magnetic and fluorescent properties of the PNNS-Tb(III) complex may be useful in biomedicine and fluorescence systems. (c) 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3121-3127, 2006.