Background: Noroviruses (NoVs) are a major cause of acute gastroenteritis in children, but prevalence and circulation of NoVs in China have not been well characterized. Objectives: To determine the dominant circulating Nov genotypes and strains associated with pediatric cases of acute gastroenteritis in Beijing, China. Study design: Fecal samples were obtained from 1126 children affected with acute gastroenteritis in Beijing from March 2004 to November 2007. NoV RNA was amplified, sequenced, and phylogenetically analyzed to determine the dominant Circulating genotypes and strains. Results: NoVs were detected in 8.88% of patients, GII.4 being the dominant genotype. Ehime/05-30 was the dominant strain during 2004-2005, whereas 2006b dominated during 2006-2007. The homology of nucleotide and amino acid sequences among full-length VP1 of 15 randomly selected NoV strains was 91.6-99.6% and 94.5-99.6%. respectively. Recombination between NoV genotypes was frequent among the isolates. Conclusions: The predominant circulating genotype of NoV infections in Beijing is GII.4 but the dominant strains of this virus responsible for gastroenteritis epidemics are evolving rapidly. A global surveillance network may be needed to identify trends in molecular evolution of NoVs for prevention of future epidemics. (c) 2008 Elsevier B.V. All rights reserved.