Aeromonas hydrophila is a bacterium, which is found in ambient water and primarily causes gastroenteritis in humans. In recent years, Aeromonas strains have been reported to cause a variety of extraintesinal infections such as ocular, respiratory, urinary tract infections. The extraintestinal infections are usually rare. However, it is pointed that these bacteria can also be a cause of prosthesis infection after a total knee prosthesis operation in the represented case. In this report, a 73-year-old female patient was represented who had been operated twice because of prosthesis infection in another hospital and still has knee ache and purulent discharge at the incision site. In the perioperative bone and soft tissue cultures, A. hydrophila was isolated and it was shown that these bacteria could be the cause of prosthesis infection except known rare causes. In this case, it was emphasized that more than one perioperative bone and soft tissue cultures should be obtained to increase the chance for definitive diagnosis in prosthesis infection.