A cluster of inmates at a correctional facility in Pinto County, Texas, had developed gastroenteritis and bloody diarrhea. The total number that became ill was difficult to ascertain as records were poor. Of 45 known illnesses, 16 had bloody diarrhea. Stool samples were collected from ill inmates, and inmates who worked in the mess hall. E. coli O157:H7 was identified in the stools of both groups. The hired mess hall staff was not tested and claimed to have no illness symptoms. Four hired staff and who did not work in the mess hall were rumored to have been ill, but none responded to investigative inquiries. A case control study linked the consumption of four food items to illness (Cajun potatoes, gravy, rice, and chili). The epidemiologic curve suggested that there had been foodborne illness transmission initially with subsequent illnesses spread from person-to-person. Six strains of E. coli O157:H7; five of these were similar enough to believe that they were all part of the same outbreak.