A long suspension bridge is usually located in a unique wind environment and accordingly strong winds at the site seldom attack the bridge at a right angle to its longitudinal axis. However, the buffeting response prediction often assumes that the wind approaches the bridge at a right angle to its longitudinal axis. This paper thus intends to investigate this subject to some extent. The conventional buffeting analysis method in the frequency domain is refined first to take into account the effects of wind inclination and yaw angle. The field measurement data, which were recorded during Typhoon Sam in 1999 by the `Wind And Structural Health Monitoring System' (WASHMS) installed on the Tsing Ma Bridge, are then analyzed to obtain both wind characteristics and structural responses. Finally, the aerodynamic and aeroelastic coefficients of the Tsing Ma bridge deck under yawed and inclined winds, which are required in the analytical prediction, are measured through wind tunnel tests and reported in this paper. The detailed comparison of the field measurement data with the analytical results, however, is still under the way, which cannot be reported in this paper.