An outbreak of E. coli O157:H7 was associated with visits to a farm in Snohomish County, Washington. A total of six illnesses were identified. One child who became ill did not visit the farm. He became ill after his sibling became ill subsequent to his sibling's visit to the farm. Children had been allowed to handle poultry, rabbits, goats, and a calf. Environmental samples from the farm were analyzed, but failed to find E. coli O157:H7.