With the introduction of the new code AS1170-2007 Earthquake actions in Australia, it was vital to establish the consequences to the design of structures. This paper investigates the differences between the old AS 1170-1993 code and the new AS 1170-2007 code with a detailed comparison of the differences between the notation, factors and the calculation of the design base shear. The assumptions made for site soil class, structural system and performance for calculating the percentage of seismic loading that the lateral resisting system are subjected to have significant implications to structures. Also revision in the calculation of the natural period of the structures has a bearing in relation to the height of structures that are most effected. By D Hegarty, Sep 2009. The full University of Sydney Research Report can be requested from the ASI library.