Instructions for preventing diarrhoea, based on a knowledge-deficit model, are a common health-promotion approach aimed at the providers of child care attending nutritional rehabilitation centres. However, there is rarely an assessment of baseline knowledge to justify the need for this type of intervention and to guide its form. This study investigated the practice and knowledge of recommended diarrhoea-prevention behaviours of caregivers of 78 malnourished children consecutively admitted to a realimentation programme. Major deficits included: 39% not boiling (or not planning on boiling) drinking water after the child reached two years of age; 35% not always washing children's hands before meals; only 17% reporting that it was rare for their children to go barefoot; and the majority breastfeeding for less than one year. However, almost all measures of knowledge, based on open and closed questions, were not related to the corresponding practice. Several types of barriers to preventive practices were reported on open questions, including, "beliefs," "children as barriers," and "time." This information may be helpful in designing more effective health-promotion programmes.