Norovirus infection is the commonest cause of outbreaks and sporadic cases of acute gastrointestinal disease in England and Wales. It is estimated that 4.5% of the population are infected by norovirus each year. Some years see more infections than others and occasionally peaks of summer time activity can occur. Current surveillance of norovirus is based on two main sources of information, routine laboratory reporting and reports of norovirus outbreaks. There are still significant barriers impeding a better understanding of the biology and epidemiology of noroviruses. Modern genetic techniques have shed light on ways in which the virus interacts with its host and evades the immune system. Some of these techniques have also led to new tools that may be useful in tracking outbreaks of norovirus, and in turn, to study the effect of potential intervention strategies, aimed at preventing or curtailing transmission within outbreaks.