Although classic rotaviral gastroenteritis occurs in children between the ages of six and 24 months, infection with rotavirus is common in all age groups, including adults. Virtually all adults have been infected, as is demonstrated by the presence of serum antibodies, but previous infection does not protect against new infection with the same or a different serotype. Rotaviral infection of adults is seen in five settings: (1) secondary contacts from pediatric cases, with variable attack rates in adults; (2) waterborne outbreaks, which are often characterized by higher attack rates in adults than in children; (3) travelers' diarrhea; (4) epidemic spread in isolated or closed populations, often in the absence of contact with children; and (5) endemic infections, which may account for 5070–10% of sporadic cases of diarrhea in adults. Frequent asymptomatic infections with rotavirus occur, and they may be important in the epidemiology of the disease. Although rotaviral infections in adults tend to be milder than those in children, death due to rotaviral infection in adults have been reported.