[en] Aging Hydraulic steel structures, especially lock gates suffer from structural deterioration with fatigue and corrosion, resulting in a reduction of their resistance. A prolonged exposure to these hazards results in a reduction of structural resistance which can lead to failure. This research presents an approach to compute the reliability of aging miter gates in the presence of corrosion and fatigue. First order reliability index method is used to calculate reliability of the structure. An example of an aging miter gate is used for demonstration.