UN reports point to a steady increase in heroin use in a number of African countries, including South Africa. South Africa also has one of the highest HIV infection prevalence rates in the world. Given the link between intravenous heroin use and HIV transmission, this study aimed to investigate HIV-related risk behaviors among heroin users in the city. A snowballing or chain referral sampling technique was used to find 239 heroin users in Cape Town who were interviewed using a structured questionnaire. Overall, 24% of all the participants reported that they had injected heroin in the past 30 days and 89% of these had shared a needle at least once during that period. Condom use was irregular among the survey participants. Three percent stated that they were HIV positive. Heroin use has become a major concern in Cape Town and may still be increasing. While injecting use still appears to be fairly limited, this has the potential to change. Further debate is required regarding the introduction of harm reduction approaches that have been found to be effective elsewhere.