Diarrhoea is one of the major causes of child morbidity and mortality especially in developing countries. Rotavirus is the most common of the causes of diarrhoea in children less than five years worldwide and has been reported as the cause of endemic viral diarrhoea in Nigeria. The aim of this study was to determine the prevalence of rotavirus among under five children presenting with diarrhoea in Benin City Nigeria. A total of four hundred and seventy (470) children below five years with diarrhoea within the preceding two weeks and who have no obvious cause of chronic diarrhoea were recruited in a study that lasted between October 2007 and October 2008. Sixty-five (13.8%) of the stools tested positive for rotavirus antigen using ELISA kit while ninety (19.2%) stools were detected by electrophoresis. RT-PCR electrophoresis using VP7 primers shows G1 = 49/90 or 54.4%, G2 = 26/90 or 28.9%, G3 = 19/90 or 21.1%, G4 = 34/90 or 37.8% and G9 = 8/90 or 8.9%. The highest occurrence was among children aged six to eighteen months. Rotavirus was found to be easily transmitted to inpatient children who previously did not present with symptoms of the virus. Vomiting was significantly associated with rotavirus induced diarrhoea than other symptoms. Majority of the 1 caregivers were semi-literates with little or no knowledge of causes of diarrhoea in their children. Breastfeeding was not protective of rotavirus infection and access to pipe borne water does not affect the rate of rotavirus infection among the population. It was concluded that prevalence of rotavirus among diarrhoea children of less than five years in Benin City has been declining in the past twenty years due to improvement in sanitation and hygiene. However, it was recommended that rotavirus vaccine be introduced as a means of protecting children of less than five years from rotavirus infection. In developing a vaccine, strains peculiar to this environment should be considered. Facilities such as PCR electrophoresis which are more sensitive in detecting rotavirus in stools than ELISA should be used in prevalence studies. Basic hygiene such as hand washing and drying, proper disposal of faeces and bed spacing should be adhered to in our children’s wards to reduce nosocomial rotavirus infection. Finally, appropriate health education should be given to caregivers to ensure use of hospital facilities for treatment of diarrhoea especially when ORS is not tolerated due to associated vomiting.