In South Africa, the frequent positioning of men's sexual behaviours as a prime driver of the HIV epidemic has generated much interest in men's sexuality. However, the relational nature of dominant male norms that exacerbate the risk of HIV transmission is inadequately understood. This study used sexual biographies to explore how men and women negotiate gendered norms and how this affects their sexual and reproductive health (SRH). A total of 50 sexual-history interviews and 10 focus group discussions were conducted with men, and 25 sexual-history interviews with women, with participants sampled from three age categories (ages 18-24, 25-55 and 55+years), a range of cultural and racial backgrounds and urban and rural sites across five provinces in South Africa. The narratives illustrate that men and women's SRH is largely dependent on the type and quality of their relationships. Men's sexuality was regularly depicted as being detached from intimacy and uncontrollable, which was premised as being opposite from and/or superior to women's sexuality and could justify men's high-risk sexual behaviours. Yet many participants also supported gender equitable relationships and endorsed accountable and healthy SRH behaviours. The narratives reveal that HIV-risky dominant male norms should be addressed relationally for the sake of better SRH outcomes.