Iowa and Minnesota health officials investigated an E. coli O157:H7 outbreak among patrons at Taco John's restaurants in Cedar Falls, Iowa, Albert Lee, Minnesota and Austin, Minnesota. Although this outbreak occurred at the same time as a Taco Bell E. coli O157:H7 outbreak on the East Coast, the Taco John outbreak was not linked to the outbreak at Taco Bell. Shredded iceberg lettuce that was served in the restaurants was determined to be the likely vehicle of transmission. The outbreak strain matched environmental samples gathered from dairy farms near a lettuce growing area in California's Central Valley.