The 465 m span Annacis cable-stayed bridge, currently under construction near Vancouver, British Columbia, will be the longest cable-stayed span in the world when it is completed in 1986. As this bridge is partially founded on soft delta deposits and is located within 80 km of a seismic source zone, its design has required careful consideration of earthquake effects. This paper reports the seismic analytical and design approaches adopted for the foundations and superstructure of the bridge. Details covered include dynamic modelling of the subsoil layers, correlation of measured surface accelerations with those predicted by computer modelling from nearby rock accelerations, earthquake risk analysis, assessment of the soil liquefaction potential, compliance of deep piles and pier translation during ground shaking, dynamic modelling of the superstructure, ductility and displacement demands in the superstructure, and details for construction.Key words: bridges, earthquake.