Rotavirus is the main cause of gastroenteritis and dehydration requiring hospitalization among infants and children. Despite the high diarrhea-related mortality rate, there are limited studies describing the prevalence of rotavirus in Turkey. The disease burden of rotavirus gastroenteritis in Turkey was assessed by active, prospective surveillance conducted in accordance with a modified World Health Organization generic protocol from 1 June 2005 through 1 June 2006. A total of 411 children aged <5 years who were hospitalized for gastroenteritis in 4 centers were enrolled. Rotavirus was identified in 53% of samples from the 338 children tested; the range for individual centers was 32.4%-67.4%. Overall, 83.8% of rotavirus-positive children were aged <2 years. Rotavirus gastroenteritis occurred year-round but peaked in the winter. G1P[8] was the most widely prevalent strain (76% of strains), followed by G2P[4] (12.8%). G9P[8] was reported in samples from 3.9% of children. These data support the need for a rotavirus vaccine in Turkey. © 2009 by the Infectious Diseases Society of America. All rights reserved.