Several members of a group became ill after eating at a restaurant in Rochester, Minnesota on February 15. No other common meals were identified among the group. Clostridium perfringens was suspected as the cause of this outbreak based on the clinical evidence. Laboratory analysis of stool specimens failed to identify the presence of a pathogen. A food preparation review suggested that the lasagna served on February 15 had been improperly cooled in a walk-in refrigerator after cooking and had not been reheated adequately prior to being served on the buffet.