The aim of this paper was to explore the nature of cocaine use and harms through a cross-sectional survey of cocaine users interviewed in the two largest Australian cities of Sydney (n = 88) and Melbourne (n = 77) between October 2004 and January 2005. The study supported previous findings that Australian cocaine users could be classified broadly into two types. The majority of cocaine users interviewed were classified as socially and economically integrated. They were young, employed, well-educated people who generally snorted cocaine on a recreational basis, typically in conjunction with other illicit and licit drugs. A second group of socially and economically marginalised users, residing mainly in Sydney, injected cocaine often in conjunction with heroin. This group reported significantly higher levels of cocaine use, cocaine dependence, criminal behaviour and human immunodeficiency virus (HIV) risk-taking behaviour. Heroin use was found to predict independently higher levels of cocaine use, criminal behaviour, needle sharing and physical problems in this sample, suggesting that increased resources and coverage for combined heroin/cocaine users may have scope for reducing cocaine-related problems in the Australian community.