Objective: To investigate the characteristics of norovirus genotype of children in Chongqing.Methods: Stool specimens of nonbacterial acute diarrhea with rotavirus antigen-negative were collected from August 2008 to July 2009.Real-time RT-PCR was used to detect the ORF1-ORF2 junction regions of norovirus.The sequencing fragments of RT-PCR products were blasted in GenBank and classified.Phylogenetic trees were constructed by the neighbor-joining method.Results: 251 of 806 stool specimens were detected for the norovirus-positive

of which 4 cases belonged to GⅠ group and 247

GⅡ group.It was most likely to occur in summer(from July to October)and in 6~12 months children.Among the sub-genotypes of GⅡ group(108 cases had been genotyped successfully)

GⅡ.4/2006b was dominant

with a constituent ratio of 62.96%(68/108)

and GⅡ.3 accounted for 25.93%(28/108);GⅡ.6

6.48%(7/108);GⅡ.2

1.85%(2/108).Besides

GⅡ.7

GⅡ.12

and GⅡ.13 were also detected.Conclusion: The prevalence of norovirus is found higher in summer in Chongqing

and GⅡ.2006b is the dominant genotype.