Our patient, with cirrhosis and chronic renal failure, represents an example of the susceptibility of a compromised host to Aeromonas infections. This patient, however, differs from previously reported cases in at least two important aspects. First, it is possible that her portal of entry was a fresh A-V fistula puncture site rather than an intestinal site. The temporal relationship of exposure to flood water prior to the onset of sepsis lends support to this possibility. Epidemiologic investigation of the dialysis center failed to reveal Aeromonas isolates from cultures of the water supply, machinery, or other patients. Second, this case is unique in that our patient developed a destructive aortic valve endocarditis resulting in valvular perforations and acute aortic insufficiency. Furthermore, this infection was initiated on what appears to have been a previously normal valve. Based on a review of the literature and the virulence demonstrated by A. hydrophila in our patient, we conclude that organisms of the genus Aeromonas are capable of inducing serious human infection. Such infections are more likely to occur in compromised hosts. A. hydrophila has accounted for the majority of reported infections.