Cable corrosion significantly decreases the ultimate and fatigue strength of cable-stayed bridges, which was parametrically studied with three different span lengths and different corrosion levels. The ultimate strength of the healthy bridge models was about 2.5 of the design loads, which satisfied the required safety of 1.7. Whereas, the ultimate strength lowered by about 25% as the loss of cross-sectional area increased due to corrosion. The elongation also decreases due to corrosion. The ultimate strength was found to sharply drop when the elongation became 1.0%. The fatigue strength of stays was studied taking a 500kN heavy lorry as the representative load. The fatigue strength sharply lowers as corrosion progresses and the severely corrode anchor cable becomes less than 4% of the healthy one.