This paper presents vibration control of bridges under moving loads using a tuned mass damper (TMD). TMD, a kind of passive type control device, has a variety of merits in that it has permanent service time, and only requires easy management and maintenance efforts and no external power supplying sources. TMD is tuned to the first dominant vertical mode and installed in the middle of bridges. The dynamic response of bridges subjected to moving loads can be obtained using moving mass model that considers the effects of the vehicle mass, thus TGV high-speed trains are modeled as 2 degree of freedom (DOF) systems consisting of the wheel and body. To show the efficiency of TMD in the case of the three-span bridge, the midpoint vertical displacements and their fast Fourier transform results are compared before and after the installation of TMD. (C) 1998 Elsevier Science Ltd.