The main focus of this paper is to show the Computational Fluid Dynamic (CFD) potentiality about the possibility to estimate the flutter derivatives of a long-span bridge. The Reynolds Averaged Navier-Stokes (RANS) simulation approach is chosen to perform the computations. It means that the turbulent flow around the bridge is not directly solved but its effect is superimposed on the mean flow adopting a specific turbulence model. The two-equation k-omega turbulence model was chosen because it represents the most balanced solution between computational cost and solution accuracy. Firstly, in order to define the simulation methodology and to test the k-omega turbulence model performance, a simple validation test con-cerning a body with a circular cross section is considered. Then the Great East Belt Bridge is chosen as case study. The bridge analysis has been subdivided into two parts. In the first part, steady simulations have been made to evaluate the bridge aerodynamic coefficients for differ-ent angles of incidence. In the second part, non-steady simulations have been performed by imposing harmonic vertical and rotational motions at the bridge center of gravity obtaining the correspondent flutter derivatives. For both steady and unsteady Great East Belt simula-tions, the computational results have been compared to experimental wind tunnel tests obtain-ing a good agreement.