Severe diarrheal infections caused by Shigatoxigenic Escherichia coli O103:H2:stx(1):eae-epsilon:ehx, O145:H28:stx(1):eae-gamma:ehx (two cases in a family), and O174:H21:stx(2c) in farm residents were traced to cattle. Molecular methods were applied to the isolation and characterization of the strains. The causative strains were also isolated from cattle samples 1 or 4 months later.