A real health priority for governments, breastfeeding has prompted the WHO and UNICEF to create the “Baby-Friendly Hospital Initiative” for maternity units regarding the “ten steps to successful breastfeeding.” This effort does not include pediatric departments. However, as the properties of breast milk enhance infant recovery, it is also important to promote breastfeeding in these units. Furthermore, few studies have analyzed the constraints of hospitalization on the breastfeeding process. The aim of this study is to identify the constraints imposed by hospitalization on the process of breastfeeding in infants aged 29 days to 6 months suffering from acute disease, during hospitalization and within a week of their return home. This prospective study was conducted between October 1 and December 31, 2008, in a pediatric department, through interviews and questionnaires from breastfeeding mothers and health professionals. 51 mother-infant pairs and 35 caregivers were included in the study. During hospitalization, direct breastfeeding was interrupted for 31 mothers. After hospitalization, 3 mothers had weaned their babies, 12 went from exclusive breastfeeding to mixed feeding, and 13 experienced difficulties. Caregivers partially meet WHO’s recommendations. The hospitalization of an infant disrupts the continuation of breastfeeding. To overcome this, actions must be taken in relation with hospitals, departments, and professionals. The study’s small sample does not prove that the original training of caregivers influence their practices.