Background: Women in sub-Saharan Africa bear the brunt of the human immunodeficiency virus (HIV) epidemic, and older married women and those in cohabiting relationships are regarded as the largest HIV risk group. Although preventing HIV infection in married or stable relationships is an international HIV prevention priority, little is known about the influence of sociocultural contexts on safe-sex practice by women, particularly older women in rural communities in South Africa. Objectives: This study aimed to examine how older women in a rural patriarchal society negotiate safer sex within marital and long-term cohabitation relationships, and their perceptions and experiences of barriers that influence condom use. Methods: Focus group discussions were conducted with married and cohabiting women aged 40–60 years recruited from primary health facilities in a rural district in Mpumalanga province, South Africa. A thematic analysis approach was used to analyse the data. Results: We found that although women reported negotiating safe sex in their relationships, they dreaded the possible consequences of suggesting condom use with their partners. Many factors made negotiating safe sex complex for these women: living in a patriarchal society where women play no part in sexual decision making, the fear of possible consequences of insisting on condom use, women’s inferior social position in marital relationships, cultural practices such as bride price, and gender inequality were the main barriers to practising safer sex. Conclusions: Older married and cohabiting women dreaded negotiating safer sex in this patriarchal society where women’s subordination is legitimized. The findings suggest that the women were at high risk of HIV infection because of their inability to negotiate condom use, or to reject forced sex and non-consensual sex. There is a need for interventions targeting older married and cohabiting couples and key stakeholders within communities to create awareness about cultural practices and beliefs that undermine women and HIV prevention efforts.