Promotion of simultaneous protection against sexually transmitted infections (STIs) and unintended pregnancy, referred to as dual protection, represents an important public health intervention. We investigated its prevalence and correlates in South Africa. A cross-sectional survey of 929 sexually active women, aged 15-49 years, was conducted in 89 public primary health care clinics, with dual method use and use of condom alone at last sexual intercourse as outcomes. At last intercourse, 12% of women were protected from both STIs and pregnancy. In multivariate analysis, higher education, being unmarried, and multiple sex partnership in the past year were predictors of dual method use, while younger age, higher education and awareness of the dual function of condoms were predictors of condom use alone. Dual protection is low in this population. The predominance of hormonal contraceptive use in South Africa means that increasing barrier method use among hormonal contraceptive users is an important strategy for increasing dual protection.