AIM: To assess the quality of counselling provided to mothers through the programme to prevent mother-to-child transmission (PMTCT) of HIV in South Africa. METHODS: Structured observations of consultations and exit interviews with 60 mothers attending clinics at three purposively selected PMTCT sites across South Africa were conducted. RESULTS: Twenty-two counsellors were observed. The general quality of communication skills was very good, and 73% of HIV-negative mothers were informed of the advantages of exclusive breastfeeding (EBF). However, only one of 34 HIV-positive mothers was informed about the possible side effects of nevirapine, and none was told what to do when it occurred. Only two HIV-positive mothers were asked about essential conditions for safe formula feeding before a decision about an infant feeding option was made. None of the 12 mothers choosing to breastfeed was shown how to position the baby correctly on the breast or asked whether they thought EBF was feasible. Fewer than a quarter of mothers expressed confidence in performing the actions required, and 85% could not define the term EBF. CONCLUSION: The poor quality of counselling in the PMTCT programme will reduce the effectiveness of these programmes. As they are being scaled up, there needs to be far more attention paid towards the counselling of mothers, especially with regards to optimal infant feeding.