The Ditrame Plus project conducted in Abidjan, Côte d'Ivoire, is aimed at the prevention of mother-to-child transmission of HIV in combining perinatal antiretroviral interventions with a systematic proposal of alternatives to prolonged breast-feeding: formula feeding from birth, or exclusive breast-feeding for 3 months then early cessation of breast-feeding. We surveyed all health care workers involved in this project in November 2003 using a self-administered anonymous questionnaire to investigate their knowledge, attitudes, and beliefs regarding the infant feeding interventions proposed since March 2001. Their knowledge regarding infant practices proposed within the study was consistent and their attitude was in accordance with the study protocol. However, proposing alternatives to prolonged breast-feeding causes difficulties for health care workers that should be taken into account when tailoring such complex interventions.