Roast beef that was served at a university graduation banquet led to an outbreak of E. coli O157:H7 infections. The resulting illnesses were relatively mild, however two persons required hospitalization. Most persons had non-bloody diarrhea, and no one developed hemolytic uremic syndrome. A matching strain of E. coli O157:H7 was isolated from an unopened package of an uncooked roast beef. The salad likely was cross contaminated by the roast beef.