In August 2012 Minnesota Department of Health (MDH) staff investigated an outbreak of gastroenteritis among individuals at an adolescent treatment facility. MDH staff interviewed patients about food consumption and illness history. Stool samples were not available for testing. Five patients were interviewed. Four met the case definition. The median duration of illness was 2.5 days (range, 1 to 6 days). Illness onset dates included August 24 (n=3) and August 25 (n=1). Information provided by facility staff indicated that 20 of 55 (36%) individuals i the inpatient program had recently developed gastrointestinal illness. No illness in outpatient program participants, who did not eat meals at the facility, was reported. An MDH sanitarian interviewed the two facility employees who work in food service. Initially, both employees were reported as being ill but during the interview, only one reported recent illness. The employee developed vomiting and cramps on August 16; recovered on August 18 and returned to work that day. Health department officials concluded that a recently ill food worker was the most plausible source of contamination although person-to-person transmission could not be ruled out.