A series of wind tunnel experiments on a long-span suspension bridge has been conducted. A proposed design for Akashi Straits Bridge having a box stiffening girder was selected as the prototype for full aeroelastic models and taut strip models to a scale of 1:350. The wind-induced response (flutter) under smooth flow and the prediction calculated from the results of sectional model tests using the strip theory are presented. It is found that agreement between experiment and prediction is very good. Response under turbulent flow and its prediction are also presented.