In March 2012 staff at Olmsted County Public Health Services (OCPHS) investigated an outbreak of suspected norovirus among patrons of a restaurant located in Rochester. Four of 9 people in the same dining party but who lived in different households ate at the restaurant on March 10. Ill persons reported symptoms of diarrhea, vomiting and cramps. No stool specimens were submitted for laboratory testing. The median incubation period was 22 hours (range, 22 to 28 hours). Duration of illness information was not available as all four cases were still ill at the time of interview. OCPHS interviewed 22 restaurant employees. Four employees reported recent gastrointestinal illness. Employees reported becoming ill on February 27, March 2, March 8, and March 10. One employee reported working as a busser while ill on March 10. Investigators concluded this was a probable outbreak of norovirus based on the incubation period and symptoms. A vehicle was not identified. Multiple ill food handlers were identified and were the likely source of contamination.