During the period December 1984 to October 1988, adenoviruses (Ads) were isolated on 119 occasions (1.6%) from stool samples of patients with gastroenteritis. By DNA restriction analysis, 85 enteric adenoviruses (EAds) were identified. Sixty-seven patients with these infections were studied, of whom 18 had Ad40, 30 had Ad41 and 19 had untyped Ad infections. The incidence of Ad infection was high in children between 6 and 11 months of age. The illness was characterized by watery diarrhea (whitish in one third of patients), continuing for a mean of 4.5 days, and vomiting, which occurred more often in patients with EAds than in other types of infection. Diarrhea, fever and vomiting were seen significantly more frequently in patients with Ad40 than in Ad41 infection. Diarrhea and vomiting were also seen significantly more frequently in patients with EAds than in Ads infection. Diarrhea, fever and vomiting were observed more frequently in patients with rotavirus than EAds infection.