BACKGROUND: This paper examines the differences in demographics, drug use patterns and self reported risk behaviours between regular injecting drug users (IDU) who report engaging in sex work for money or drugs and regular injecting drug users who do not. METHODS: Cross sectional data collected from regular IDU interviewed as part of the New South Wales (NSW) Illicit Drug Reporting System (IDRS) in 2003 were analysed. RESULTS: IDU who reported engaging in sex work were more likely to be female, and identify as being of Aboriginal and/or Torres Strait Islander descent. They initiated injecting drug use at a significantly younger age and were more likely to report injection related problems than IDU who had not engaged in sex work. There were no differences in the drug classes used, but findings suggested that the sex workers tended to be more frequent users of crystalline methamphetamine (ice) and benzodiazepines. CONCLUSION: The similarities between these groups were more striking than the differences. Further research, examining a larger sample is needed to clarify whether injecting drug users who are sex workers have heavier use patterns.