We investigated mobile phone usage amongst HIV-positive pregnant women attending antenatal services in a primary care clinic in Johannesburg (nā€‰=ā€‰50). We conducted a semi-structured interview and asked them about their mobile phone, Internet and email use. The median age of the women was 28 years, 36% had moved one or more times in the past year, and most were employed or recently employed, albeit earning low wages. Nearly all women (94%) reported that they did not share their phone and 76% of the SIM cards were registered to the woman herself. The median time with the current phone was one year (range 1 month-6 years) and the median time with the current phone number was three years (range 1 month-13 years). Even though 42% of the participants were from outside South Africa, they all had mobile phone numbers local to South Africa. About one-third of respondents reported Internet use (30%) and about one-fifth reported using email (18%). Overall, 20% accessed the Internet and 10% accessed email on their mobile phone. Mobile phone interventions are feasible amongst HIV-positive pregnant women and may be useful in prevention of mother-to-child transmission of HIV (PMTCT). Email and Internet-based interventions may not yet be appropriate.