In July, 2005, a cluster of 11 matching isolates of E. coli O157:H7 was investigated. A matching strain of E. coli O157:H7 was isolated from a consumer sample of ground beef. Eventually 63 related cases were identified and an additional sample of raw ground beef showed the presence of a matching strain of E. coli O157:H7. This investigation led to two recalls of ground beef that had been processed by one grinding plant. Traceback to slaughter facilities was limited by inadequate records and package labels. Recalls were made, but references to these could not be found.