This study examined the evolution and duration of diarrhoea episodes observed in a community setting, with regard to symptoms and carers' responses. The study group comprised 1156 children, aged 0-36 months, who were followed-up with twice-weekly home visits in 30 sampling areas in the city of Salvador, northeast Brazil. A total of 2403 diarrhoea episodes (mean duration: 2.9 days) were recorded. The number of soft/liquid motions per day (3.6) did not vary significantly with duration, but other symptoms were more commonly reported in the longer episodes. However, when the data were analysed by day of the episode, rather than the episode's overall duration, the reported frequency of fever and vomiting declined significantly with time. During the course of an episode, rehydration, medication and care-seeking also showed a decline in frequency after the first or second week. As episodes continue, less rehydration and medical care are provided by carers, whereas they ought to be maintained because of the continued purging and cumulative effect of the symptoms. Since most cases of diarrhoea are managed at home, it is important to understand how to encourage better management of the longer episodes, which cause an increasing proportion of mortality in some countries.