In 1989, the first year of coordinated Vibrio surveillance in four Gulf Coast states (Alabama, Florida, Louisiana, and Texas), 121 infections were reported. These included 34 V. parahaemolyticus, 30 V. cholerae non-O1, 18 V. vulnificus, 9 V. hollisae, 7 V. alginolyticus, and 7 V. fluvialis. Fourteen patients had primary septicemia, 71 had gastroenteritis, and 29 had wound infections; 7 had other or unknown illnesses. Sixty-six patients were hospitalized, and 9 died. All patients with primary septicemia, but only 17% of those with gastroenteritis, were known to have an underlying illness (P < .001). Among patients for whom data were available, 67% with primary septicemia and 74% with gastroenteritis ate raw oysters in the week before illness began. Of 50 patients with data on where oysters were obtained, 42 (84%) ate them at oyster bars or restaurants. These data provide evidence that in the Gulf Coast region raw oyster consumption is an important cause of Vibrio-associated gastroenteritis among adults without underlying illnesses.