Investigation of outbreaks of food-borne disease requires close cooperation between the health service and the food control authorities. The primary objective is to stop the outbreak and provide a basis for specific control and preventive measures. The investigation consists of the following steps: To confirm the existence of an outbreak and notify all authorities involved; to describe the outbreak according to the variables of time, place, person, and agent; to establish an interim diagnosis and identify the etiological agent responsible; to assemble all information and establish hypotheses about the source of infection using inspections, laboratory investigations, and pilot interviews; to test the hypotheses by laboratory-based methods and analytic epidemiological approaches; to eliminate the source of infection, implement preventive measures, and control that they are efficient; to report the results.