Noroviruses (NoVs) are a leading cause of viral gastroenteritis in humans. In the present study, the association between NoV susceptibility and the ABO histo-blood group was studied during 2 outbreaks of acute gastroenteritis in military units in Israel caused by genogroup II (GII) NoVs. The findings demonstrate that, unlike for genogroup I of NoV, there is no association between the ABO histo-blood group and clinical infection with GII NoVs. This is the largest study to test the association between NoVs, proven clinical infection with GII, and the ABO histo-blood group.