BACKGROUND: Dual protection is recommended for prevention of unwanted pregnancies and protection against sexually transmitted infections, including HIV. It is critical for HIV-negative women to prevent seroconversion and HIV transmission to their infants during pregnancy and breastfeeding. METHODS: Women were followed up after delivery, monthly for the first 9 months and then 3-monthly to 24 months, in a cohort study investigating postnatal HIV transmission. Study nurses discussed family planning, including condom use, at each visit. Contraceptive methods used since the last visit were recorded. All women knew their HIV status, and most women breastfed for a minimum of 6 months. RESULTS: Among 1 137 HIV-positive and 1 220 HIV-negative women the most common contraceptive method was the hormonal injectable; few women used condoms alone or as dual contraception (0 - 3 months 6.8%; 7 - 12 months 16.3%; 19 - 24 months 14.4%). Compared with uninfected women, HIV-positive women were more likely to use condoms in years 1 and 2 after delivery (adjusted odds ratio (AOR) 1.72, 95% confidence interval (CI) 1.38 - 2.14, p<0.001; AOR 1.61, 95% CI 1.15 - 2.25, p=0.006 respectively). Compared with women with a flush toilet, those with a pit latrine were less likely to use condoms in years 1 and 2 (AOR 0.22, 95% CI 01.7 - 0.28, p<0.001; AOR 0.27, 95% CI 0.19 - 0.39, p<0.001). Older women were more likely to use condoms in the first postpartum year (AOR 1.78, 95% CI 1.03 - 3.09, p=0.040). CONCLUSIONS: More creative ways of promoting condoms and dual contraception need to be found if new HIV infections, in women and children, are to be prevented.