In recent years, a number of studies have been conducted to analyze wind-induced vibrations of a bridge using computational fluid dynamics (CFD). Previous studies have been limited to analyzing two-dimensional sections only, and three-dimensional (3D) analyses of entire bridges have not yet been performed. In this study, a CFD program with fluid-structure interaction is developed to perform buffeting analysis of a 3D cable-stayed bridge. The FEM formulated by the Galerkin least-squares method and arbitrary Lagrangian-Eulerian method are used to perform fluid-structure interaction CFD. The spectral representation method is used to generate the time series turbulence, which is applied to the inlet boundary condition. A supercomputer is used to reduce the large computing time. The analysis model of an existing cable-stayed bridge, which contains an ambient atmospheric region, has been used to calculate the dynamic responses of bridges and the detailed flow of wind. The results of the 3D CFD analysis of the bridge are compared with the results of conventional frequency domain buffeting analysis. The results are essentially in good agreement with those of the conventional analysis. The numerical method developed in this study will be an efficient alternative to wind tunnel tests for verifying wind flow, wind loading, and structural vibrations. (C) 2014 American Society of Civil Engineers.