INTRODUCTION AND AIMS: The study examines risk behaviours of the users of syringe dispensing machines (SDMs) and evaluates the usefulness of these machines in providing injecting drug users (IDUs) with sterile injecting equipment. DESIGN AND METHODS: Self-administered questionnaires were used among users of SDMs in an Area Health Service of Sydney. RESULTS: The majority of the 167 participants reported being happy with the quality of the SDM services. Problems identified with machines were that they were often broken or jammed (32.8% respondents), not in the right place (21.9%) or require money (16.7%). Just over half (50.9%) of the IDUs use SDMs only from 5 p.m. to 9 a.m., the time when almost all other outlets for accessing sterile injecting equipment remain closed. Relatively young IDUs (age < or = 30 years) were more likely to prefer SDMs over staffed needle syringe programmes (NSPs) compared with older users (age > 30) and to identify stigma (a desire to hide their identity or not liking the way people treat them at staffed NSPs or chemists) as a main reason for using these machines. Primary users of SDMs do not differ from primary users of NSP/chemists in terms of sharing of needles. Those users who had shared in the last month were nearly four times as likely to have never used condoms in sexual encounters over that period (95% confidence interval: 1.2 - 14.5). DISCUSSION AND CONCLUSION: SDMs appear to complement other outlets of NSPs. Providing free-of-cost equipment from SDMs should be considered carefully, as needing money to buy equipment was a reason given for sharing of needles by 35% of those who shared.