The first outbreaks of Norwalk virus gastroenteritis in Minnesota were confirmed in 1982. Since then, Norwalk-like caliciviruses have been recognized to be the most common cause of foodborne disease outbreaks, accounting for 41% of all confirmed foodborne outbreaks in Minnesota from 1981-1998. Although laboratory confirmation of caliciviruses in stool samples was not attempted in most of these outbreaks, all conformed to epidemiologic criteria for defining outbreaks of Norwalk virus. Since 1996, the availability of polymerase chain reaction testing at the Minnesota Department of Health has allowed for the confirmation of calicivirus infection among patients involved in epidemiologically defined outbreaks of viral gastroenteritis. Results have confirmed the usefulness of characterizing foodborne disease outbreaks by epidemiologic criteria and also confirmed the importance of human caliciviruses as the leading cause of foodborne disease outbreaks in Minnesota.