Abstract: Group F Vibrio was detected in 15 of 283 fecal specimens collected in 1984 by the diarrhea monitoring groups throughout Xuzhou City, giving a detectable rate of 5.30%, which was equal to that of invasive E. coli and next only to that of Bacillus dysenteriae. Familial clustering infection had been demonstrated in one family with a detactable rate of group F Vibrio much higher than that observed in Dacca.