Consumption of ground beef purchased through various outlets of a grocery store chain was associated with an outbreak of E. coli O157:H7 infections. The ground beef was consumed through a variety of preparations such as hamburgers, casseroles, spaghetti sauce, tacos, etc. E. coli O157:H7 matching the strain isolated from case-patients was isolated from consumer product and returned product samples. Additional strains of E. coli O157:H7 were also isolated. The ground beef was recalled by the grocery store chain and subsequently by the national distributor/beef supplier.