The authors describe the mass incidence of haemolytic-uraemic syndrome (HUS) in five children from one community. They draw attention to the importance of collaboration with communal hygienists and food hygienists in epidemiological investigations of haemolytic-uraemic syndrome. In view of the necessity of early collection of biological material, specimens and examination of contacts, the authors draw attention to the importance of adhering to compulsory notification of HUS.