Within 48 hours of the University of Pennsylvania and Cornell University football game in Philadelphia, on September 19, students and other spectators developed gastrointestinal illness. Ninety two percent of the ill students reported purchase of soda with ice from the stadium concessionaire. Stool samples were analyzed; there was no evidence of bacterial agents. A 27-nm virus-like particle was identified in a stool sample from an ill student. None of the University of Pennsylvania football team was affected by gastroenteritis until a week later, when at that time, during practice, the team used the same ice that had been supplied to the stadium concessionaire the week before. A separate, documented, outbreak of gastroenteritis occurred among people who attended a museum fundraiser in Wilmington, Delaware. The ice was traced to the same manufacturer that had supplied the concessionaire in Philadelphia. The manufacturer's ice was made from well water. The wells had been recently flooded by waters from Conestoga Creek. There were high concentrations of fecal coliforms in both the ice and the well water. An increase in gastronenteritis was noted among residents along Conestoga Creek who obtained their water from wells. Based on distribution records and the Pennsylvania attack rate, more than 5000 persons may have become ill. The ice and products made with the ice were recalled.