From January 2004 to December 2005, a subset of stool specimens (n = 189) from patients who attended an urban hospital in Bangladesh, in which no pathogen was detected, was tested for the presence of noroviruses by conventional reverse transcription-polymerase chain reaction (RT-PCR). Norovirus RNA was detected in 37 samples (19.6%) in the no-pathogen-detected samples and the estimated overall norovirus detection rate was 8.5%. Diarrhea was generally moderate in the norovirus-infected patients and vomiting was the most common feature among them. Genetic analysis indicated that the GII genogroup was the most predominant norovirus strain (82.4%). The GI strain was found in 17.6% of samples and no cases of GIV were detected. This study indicates that a remarkable proportion of the diarrhea patients is hospitalized due to norovirus infection. Therefore, routine diagnosis of this virus in hospitalized patients is required. Since our study was based on hospitalized patients, community surveillance would be helpful to estimate the true burden of the virus in the country. The data regarding the genetic information of the circulating norovirus strains would be very useful for the norovirus vaccine development programs.