Sick kitchen workers were found to be the cause of a large outbreak of Norovirus in Michigan. Almost 400 people became ill after eating at the Carrabba's restaurant in January and February. Kitchen workers, including a line cook, had worked while ill. Two types of studies, descriptive and analytical, were performed to determine the size of the outbreak and to determine common exposures. Two foods showed statistical association with illness, the antipasti platter and garlic mashed potatoes. An environmental inspection of the restaurant found sanitation issues beyond sick employees including deficiencies in: hand-washing practices; surface sanitation; temperature control; and sink maintenance. Once the restaurant was disinfected with a bleach solution, it was allowed to reopen.