From 20 April through 13 May 1992, 9 children were hospitalized with hemolytic-uremic syndrome in Lombardia, Italy, where only 14 cases of this syndrome had occurred in the preceding 4 years. Cases were scattered in a large area encompassing five provinces, and the source of the outbreak was not identified. Eight patients needed dialysis, and there was 1 death. Seven of the 9 cases were examined for evidence of infection by Vero cytotoxin (VT)-producing Escherichia coli (VTEC). Six children had serum antibodies to the lipopolysaccharide of E. coli O111, and a VT-producing E. coli O111:NM was isolated from stool in 1 case. This is the first outbreak of VTEC infection recognized in Italy and the first associated with an E. coli serotype other than O157:H7.