A total of 256 infants younger than three years, hospitalized by acute diarrhea, was studied from December 1983 to May 1984. Presence of rotavirus in their feces was demonstrated in 27.7%; in 4.3% of them, rotaviruses were associated with other agents. Vomiting followed by respiratory symptoms and fever were the main clinical symptoms observed in such patients, and in most of them diarrhea was profuse and liquid. Influence on infection by rotavirus of maternal feeding, hygienic-sanitary conditions, presence of domestic animals, and so forth, could not be demonstrated.