We analyse the determinants of equity agency costs for the top 500 Australian listed firms. Data are collected over four one-year periods (2004, 2005, 2010 and 2011) and analysed using both pooled OLS regression and two stage least squares regression within a random effects panel data model. Analysis covers the full four-year period, the pre global financial crisis (GFC) sub-period (2004 and 2005) and the post GFC sub-period (2010 and 2011). Shareholding, board characteristics and debt financing are found to have an impact on agency costs though there is evidence of some change in these relations with the onset of the GFC, particularly with respect to the impact of insider ownership and board size. ©2012 Elsevier B.V. All rights reserved.