The aim was to explore and describe characteristics of males' social and sexual networks in a South African peri-urban community. Twenty in-depth interviews were conducted with men participating in a larger quantitative study where the median age of the men was 28.7 years and almost 56% had some high-school education, 17.2% were unemployed and 94.7% were not married. A Thematic Question Guide with open-ended questions was used for the interviews. A thematic content analysis was conducted to explore the characteristics and dynamics of social and sexual relationships among these men. A high number of temporary and stable concurrent female sexual partners, geographic mobility and high levels of unprotected sex were common. Increased status as a man and lack of trust in women's fidelity were given as important reasons for concurrent female sexual relationships. Strong social networks within male core groups provided economic and social support for the pursuit and maintenance of this behaviour. Concurrent sexual relationships in combination with high viral loads among newly infected individuals unaware of their HIV status create an extremely high-risk environment for the spread of HIV in this population. Interventions targeting men at high risk of HIV need to challenge current societal norms of masculinity to help promote individual sexual risk reduction strategies. Such strategies should go beyond increasing condom use, to include a reduction in the number of concurrent sexual partners.