Despite the biomedical potential to eliminate vertical HIV transmission, drug adherence to short regimens is often sub-optimal. To inform future programmes, we reviewed evidence on the factors influencing maternal and infant drug adherence to preventing MTCT drug regimens at delivery in sub-Saharan Africa. A literature review yielding 14 studies on adherence to drug regimes among HIV-positive pregnant women and mothers in sub-Saharan Africa was conducted. Rates of maternal adherence to preventive drug regimens at time of delivery varied widely across sites between 35 and 93.5%. Factors most commonly associated with low adherence to antiretroviral therapy (ARV) prophylaxis for preventing MTCT at the health system level include giving birth at home, quality and timing of HIV testing and counselling, and late distribution of nevirapine (NVP). Socio-demographic and demand-side factors include fear of stigma, lack of male involvement, fear of partner's reaction to disclosure, few antenatal (ANC) visits, young age and lack of education. With the implementation of the newly published WHO guidelines recommending triple-drug ARV regimen during pregnancy and breastfeeding for all women with HIV, it is important that women are able to adhere to recommended drug regimens. Service improvements should include clear and timely communication with women about the benefits of combined regimens and greater emphasis on patient confidentiality. Efforts must be made to help women overcome barriers that reduce adherence, such as financial logistical challenges, social stigma and women's fear of violence.