In July 2017 Yakima County Health District officials investigated an outbreak of suspected norovirus among 9 people who ate at a fast-food restaurant on July 16 or July 17. Two people saw a health care provider. No one was hospitalized and no one died. The median incubation period was 34.5 hours (range, 13 to 47 hours). All 9 ill people reported vomiting and diarrhea. There were at least 2 ill food workers.