Norovirus causes severe gastroenteritis requiring hospitalization especially in children less than five years of age both in developed and developing countries. Therefore, we aimed to investigate the incidence of norovirus (NoV) in 0-5 years old children with acute gastroenteritis in two large hospitals in Ankara, Turkey. Stool samples were obtained from 1000 (413 female, 587 male) children between 0-5 years old with acute gastroenteritis who attended to the Department of Paediatrics, Ministry of Health Ankara Training and Education Hospital and affiliated hospital of Gazi University Faculty of Medicine between October 2004 and June 2011. Antigens of norovirus GI and GII genogroups in the stool specimens were detected by ELISA (RIDASCREEN Norovirus (C1401) 3rd Generation, R-Biopharm, Germany). Norovirus GI and GII antigens were determined in a total of 141 (14.1%) samples, of them 62 (15%) were female and 79 (13.5%) were male, yielding no statistically significant difference (p> 0.05). The highest NoV positivity was detected in children between 12-23 months (17.1%), however there was no statistically significant difference between ELISA positivity and age (p> 0.05). NoV detection rate was highest in 2007 (18.4%) and in 2009 (18%), and the difference regarding ELISA positivity among the study years was not statistically significant (p> 0.05). The prevalences of norovirus infection in spring, summer, autumn and winter were 13.8%, 17.7%, 14.7% and 11.2%, respectively. Therefore no seasonal variation was found in the incidence of norovirus infection. However when the monthly prevalence was analyzed, a statistically significant difference was found (p< 0.05) between the rate of norovirus infection in july (24.2%) and december (4.1%). When evaluating the clinical symptoms, all of 141 patients (100%) had diarrhoea, while 72 (51.1%) had vomiting. Stool samples were also evaluated for the presence of parasitic and bacterial agents. Coinfection rate with parasites was detected as 3.3% (4/122; norovirus + Entamoeba histolytica in three cases, norovirus + Enterobius vermicularis in one case), while no pathogenic bacteria were isolated from norovirus positive stool samples. The prevalence rate of 14.1% for NoV GI/GII infection detected in this retrospective study including 0-5 years old children in Ankara for 20042011 period was thought to reflect the regional data and would contribute to national epidemiological data. We anticipate that the incidence of norovirus will increase in 0-5 year old children as a result of increasing use of rotavirus vaccine in Turkish children. It was concluded that, NoV antigen detection tests should be used in routine laboratories for appropriate diagnosis of sporadic and/or epidemic norovirus infections.