Lack of access to condoms presents a fundamental barrier to HIV prevention across most of sub-Saharan Africa. One strategy to enhance the accessibility of condoms is to promote their informal distribution outside of health facilities through existing social networks. To investigate the prevalence and practices of informal condom distribution, we administered a questionnaire to individuals procuring condoms at 12 public health facilities in four regions of South Africa. Of the 554 individuals interviewed, 269 (48%) reported either giving or receiving condoms informally in the month before the study. In multivariate analysis, reporting informal condom distribution was associated with increased education, male gender, multiple sex partners and recent condom use. The specific practices involved in giving or receiving condoms differed between males and females, with women more likely to involve family members and men more likely to involve friends. These results indicate that informal condom distribution is surprisingly common among individuals procuring public sector condoms in South Africa, and begin to suggest the gendered nature of informal condom distribution networks. While these findings require confirmation in other populations, the practices of informal condom distribution described here provide an excellent opportunity for enhancing condom accessibility and delivering other interventions for HIV prevention.