The Pinellas County Health Department, in Florida, received a report of illness in a nine-year-old who had attended a week-long session at a day camp; the child had come in contact with animals in the camp's petting zoo. Forty-five children, in grades 2 through 8, had attended week-long camp sessions between May 21 and August 17. At the camp, the children had been encouraged to have contact with goats, sheep, and a llama. Staff members supervised the children, cared for the animals, and encouraged the children to wash their hands after animal contact. Campers were not instructed in appropriate hand washing technique; staff members were stationed too far away to assure that complete hand washing was done. E. coli O157:NM was not only isolated in the children's stool, but samples from the goats and from the soil yielded the same strain of E. coli O157. One isolate from a goat had a different PFGE pattern from the outbreak strain. The petting zoo was closed beginning June 8. The zoo animals were placed in quarantine. Outbreaks of illness related to animal contact in petting areas are relatively common. These settings often are not in compliance with national guidelines. This outbreak occurred despite the fact that day camp leaders were familiar with certain recommendations to reduce human illness in animal settings.