AIMS: To examine the effects of a series of injecting drug users' (IDU) characteristics and drug use behaviours upon the self-reported oral health of a sample of IDU. DESIGN: Cross-sectional survey. SETTING: Melbourne, Australia. PARTICIPANTS: A total of 285 IDU recruited through needle and syringe programmes, snowballing and outreach across six sites. MEASUREMENTS: Structured survey that collected information on current drug use patterns, self-reported blood-borne virus status and general health factors, including open-ended questions on past-year dental health problems. FINDINGS: Sixty-eight per cent of the sample reported dental problems that were commonly severe and caused dental pain. Despite these reported problems, almost half the sample had not visited the dentist in the 12 months prior to the survey. Participants who were older, and reported homelessness, not eating every day and more common injection of amphetamines rather than heroin in the previous month, were more likely to report having a past-year dental problem. CONCLUSIONS: Dental problems in IDUs are common but few receive treatment. Further, those using amphetamines, with poor housing, hygiene and poor nutrition, are most at risk. Programmes designed to improve the oral health of IDU need to be developed and implemented in a manner amenable to the varying social circumstances of this marginalized group in the community.