Norovirus infections in diarrhea patients attending an urban and a rural hospital in Bangladesh were investigated. A total of 953 fecal specimens from both children and adults collected during 2010–2014 were tested for the presence of norovirus using real time PCR. One fourth (25%) of the specimens were positive for norovirus RNA which was identified both in children and adults. Norovirus was associated with short duration of diarrhea, high abdominal pain, and more moderate to severe dehydration when compared with rotavirus infections. Norovirus GII (69%) was the most prevalent genogroup followed by GI (18%), mixed GI/GII/GIV (11%), and GIV (2%). Among GII genogroup, GII.4 (42%) was the most prevalent genotype followed by GII.3 (21%), GII.6 (7%), GII.7 (6%), and GII.21 (6%). GII.4 and GII.3 strains were frequently identified (82% and 75%, respectively) in children <2 years of age and less commonly (16% and 15%) in adults more than 18 years of age. The present study reinforces the importance of norovirus-associated hospitalizations both in children and adults. The dynamic molecular epidemiology of norovirus requires routine strain surveillance to identify changes in prevailing strains.