In some parts of the world up to one-half of all deaths in young children are attributable to dehydration associated with diarrhoea. As a countermeasure, mothers in underdeveloped countries are being successfully taught to give oral rehydration solution at home. There are, however, serious doubts as to whether mothers give their children enough. The focus of our investigation was a methodology capable of establishing the exact quantity of fluid administered by unsupervised mothers at home. Accurate quantitative data are essential for programme planning and evaluation. In our sample of 44 cases, only two children received more than 90 ml kg-1 day-1. The mean observed value was 44 ml kg-1 day-1 (SD 28.4); well below the recommended dosage. Preliminary data were also gathered on natural consequences which may discourage use of ORS such as vomiting, increased frequency of watery stools, and distaste for the solution.