An outbreak of E. coli O26 involved children who attended day care programs in Ellensburg, Washington. Foursquare Church Daycare and Preschool, Kids Learning Center and Little Tot Town Day Care were the child care programs affected by the outbreak. The first reported child-patient was the only one who did not attend day care. The case-siblings who attended the Foursquare Church Daycare and Preschool were related to a child who attended one of the other day care programs. The health department inspected the facilities and required that all children undergo stool testing. Children were not readmitted to the programs until their stool samples proved clear of E. coli O26.