Morphologically distinct caliciviruses of human origin were first found in stools of children with gastroenteritis in 1976. Sapporo virus, or human calicivirus Sapporo, with typical surface morphology was first detected during a gastroenteritis outbreak in a home for infants in Sapporo, Japan, in 1977. Since then, morphologically and antigenically identical virus has been detected frequently in the same institution in association with outbreaks of gastroenteritis. Sapporo virus is widely distributed worldwide, as evidenced by the appearance of antigenically or genetically similar viruses and seroepidemiologic findings. Sapporo virus plays an important role in outbreaks of infantile gastroenteritis and is less important in foodborne outbreaks. Sapporo virus has been approved as the type species of the genus "Sapporo-like viruses in the family Caliciviridae. The history of and recent findings, as obtained by newly developed techniques, about Sapporo viruses are presented.