We characterized two Shiga toxin-producing Escherichia coli (STEC) O86:HNM isolates from a patient with hemolytic uremic syndrome (HUS) or bloody diarrhea. Both of them did not possess the eaeA gene. However, the isolate from a HUS patient carried genetic markers of enteroaggregative E. coli (EAEC) and showed aggregative adherence pattern to HEp-2 cells. The other isolate from bloody diarrhea, which was negative with EAEC markers, was diffusely adhered to HEp-2 cells. The stx2 gene in both E. coli O86:HNM strains was encoded in each infectious phage, which was partially homologous to that of strain EDL933, a STEC O157:H7. These results will help to explain the genotypic divergences of STEC.