Two Escherichia coli O-rough:K1:H7 strains producing verotoxin 1 that wore isolated from stool samples of two travelers with diarrhea who consulted our clinic after trips to the Indian Subcontinent and Central America were characterized. Both strains were sorbitol negative, the same phenotype presented by E. coli O157:H7, but in contrast they were β-glucuronidase positive. Low-frequency restriction analysis of chromosomal DNA and pulsed- field gel electrophoresis and repetitive extragenic palindrome-PCR showed that both strains were epidemiologically related. The illness was self- limited in both cases but involved long-duration, watery diarrhea (10 to 50 days) accompanied by abdominal cramps and flatulence. This serotype should be taken into account as a possible cause of traveler's diarrhea.