We report the case of an elderly immunocompetent patient with Aeromonas hydrophila bacteremia without evidence of portal of entry. Despite several risk factors for a poor outcome, such as impaired renal function, two positive blood cultures, and community-acquired infections, the patient survived. Antimicrobial susceptibility was normal. Unknown polycystic liver disease was discovered and misdiagnosed as a hepatic abscess at the time of the bacteremia which was confirmed by repeated CT scans. Because of the absence of other risk factors for Aeromonas bacteremia, hepatic polycystic disease may take part in the onset of Aeromonas sp bacteremia as well as immunosenescence.