Laboratory workers at a large medical center in Texas developed gastroenteritis after eating muffins and doughnuts that were left anonymously in the break room. An identical strain of Shigella dysenteriae, type 2, was isolated from the stool samples of eight persons. These were a genetic match to the Shigella dysenteriae that was isolated from a partially eaten muffin. The source of this outbreak was likely the laboratory's stock culture which was used to contaminate the pastries.