Acute gastroenteritis is one of the most common diseases, affecting children worldwide. Viruses are recognized as a major cause of this disease, particularly in children. Since the Norwalk virus was identified as a cause of gastroenteritis, the number of viral agents associated with diarrheal disease in humans has progressively increased. Rotavirus is the most common cause of severe diarrhea in children under 5 years of age. Human astroviruses, caliciviruses and enteric adenovirus are also important etiologic agents of acute gastroenteritis. Other viruses such as toroviruses, coronaviruses, picobirnaviruses, Aichi virus and human bocavirus are increasingly being identified as causative agents of diarrhea. Vaccination against rotavirus could prevent cases of severe diarrhea and reduce the mortality attributable to this disease.