A highly nonlinear response and a self-regulated process are usually associated to the dynamic response of a flexible riser. In addition, the formation of vortices shedding from the riser related to Vortex-Induced Vibration (VIV) may adversely affect its structural integrity. In this paper a response prediction model for oscillating flexible risers is presented. It is based on the Finite Element Method (FEM) and a harmonic model for the prediction of the cross-flow forces. An increased mean drag coefficient model and amplitude-dependent lift coefficients are also considered. The simulation results are compared with experimental data obtained from a 35-meter riser model. Good agreement in amplitude response is observed in these comparisons.