For over thirty years urban growth policies in Australia have focused on increasing residential densities around public transport nodes as a method of addressing environmental issues. There has been significant debate about the role of density in influencing public transport use. A major gap within this area is that research has focused on the macro-level with minimal analysis at lower spatial levels. This research attempts to fill a gap in our knowledge by assessing the relationship between urban density and public transport use, particularly trains, at different spatial levels. The analysis uses data across the Sydney metropolitan area to assess the implications of the density-public transport debate. The research concludes that residential density is not as important as socio-economic factors in influencing public transport use. The study finds that at the macro level the notion of increasing densities increases public transport use is plausible, yet at the micro level the relationship between high density housing and public transport use is more complex. This suggests that the promotion of higher densities as a means to increase public transport use needs to be re-assessed.