We compared real-time polymerase chain reaction (PCR) and a newly developed enzyme immunoassay (EIA) for the detection of noroviruses (NoV) in 70 stool samples taken from outbreaks and sporadic cases of acute gastroenteritis. The real-time PCR classified more samples as positive than the EIA (26 versus 10) and detected more outbreaks of NoV (six versus two). Real-time PCR offers rapid and sensitive diagnosis for both sporadic cases and outbreaks of NoV gastroenteritis and, by comparison, the reduced sensitivity and specificity of the EIA will result in negative samples having to be tested by PCR. This delay might undermine current infection control procedures, lead to further dissemination of infection and increase healthcare costs.