In this paper, we examine trends and differentials in diarrhea prevalence and treatment in Brazil between 1986 and 1996. Our results indicate that there was a very modest decline in diarrhea prevalence in Brazil over this ten-year period. However, treatment with oral rehydration therapy (ORT) increased greatly. Although deaths due to diarrhea were reduced, high disease rates continue to place a large number of children at risk of adverse nutritional and developmental outcomes. There were dramatic differences in diarrhea prevalence across socioeconomic groups and regions that persisted over time, although the large regional differential in ORT treatment that was present in 1986 had disappeared by 1996. The persistence of high rates of diarrhea indicates that reducing the prevalence of the disease continues to be a major public health priority. The large differential in the prevalence of diarrhea across socioeconomic groups and regions means that interventions to prevent the disease should be targeted towards the most disadvantaged segments in Brazil, which also face the highest child mortality rates.