This study aimed to determine the genotypes of NSP4 in children with acute rotavirus diarrhea and evaluate serum antibody titers to NSP4 in different age groups in Shanghai, China. A total of 171 stool specimens were collected from hospitalized patients < or =5 years of age who had acute rotavirus diarrhea between January 2003 and December 2006. Serum samples were collected from healthy individuals, including 200 for 0-60 months of age and 30 for over 5 years of age. NSP4-B type was the single predominant genotype during 2003-2006 in Shanghai. The titers of NSP4 specific IgG antibody increased with age after birth and peaked during 12-23 months of age, thereafter dropping to a level as low as that in the first 5 months of age. However, high levels of antibody against whole rotavirus were maintained in older children over 5 years of age and in adults. Information on prevalence of NSP4 genotypes in this area of China provides useful data for formulating vaccine policy. Short antibody immune memory compared with that induced mainly by rotavirus structural proteins indicated the protective effect against rotavirus may not persist long term if a single NSP4 protein is applied as the rotavirus vaccine.