The paper describes the epidemiology, risk factors and impact on pregnancy outcome of syphilis in pregnant women in rural South Africa. Prevalence was determined from laboratory records. A case-control study of 200 women (50 cases with syphilis) was done to investigate possible risk factors. To determine the impact on pregnancy outcome, and to evaluate the effect of treatment, a retrospective cohort was constructed. Overall prevalence of syphilis was 6.5%; it was highest in the urban antenatal clinic (9%). The odds ratios for syphilis in women gravidity 3–5 compared to gravidity 6 was 3.2 and 2.3 compared to women with gravidity 2 or less. For women with a previous birth, those with a previous perinatal death were 3.2 times more likely to have syphilis after adjusting for other risk factors. Pregnancy outcome was available for 187 women. The adjusted odds ratio of an adverse pregnancy outcome in women with syphilis was 11.8. All still births occurred in women with syphilis. The prevalence of syphilis is high in this rural area and screening should be applied to all women. Although screening was comprehensive, less than half of the detected cases were fully treated and a poor perinatal outcome ensued. On-site testing for syphilis at the time of booking would allow treatment to start immediately.