A case of recurrent sepsis due to Aeromonas hydrophila in a patient with acute myelogenous leukemia is reported. The patient's first infection leading to bacteremia followed contamination of a mosquito bite by stagnant water. After recovery from the first bacteremia, the patient again became septic with a second strain of Aeromonas hydrophila, which again responded to antimicrobial therapy. It is hypothesized that contamination of the local water supply may have led to the establishment of a gastrointestinal carrier state that produced the second bout of Aeromonas sepsis when the patient was markedly leukopenic. The importance of the oxidase test to differentiate Aeromonas species from members of the family Enterobacteriaceae is re-emphasized.