The etiology of viral diarrhoea in children in the Saudi Arabia is incompletely characterized. Available data suggest that the causative agents are found at approximately similar frequencies here as elsewhere. This book addressed; the epidemiology of diarrhea viruses in pediatric populations initially rotavirus, enteric adenovirus, astrovirus and norovirus. Furthermore, the existing data on these Viruses in KSA and, characterization for genotypes using molecular methods in KSA.