BACKGROUND AND PURPOSE: Bacteremia due to Aeromonas sobria complex is an uncommon clinical presentation, associated with a high mortality rate. This retrospective study reviewed the clinical manifestations and prognostic factors of A. sobria complex bacteremia. METHODS: From September 2001 to August 2006, all adult patients with A. sobria complex bacteremia treated at a tertiary medical center in Taiwan were included. Antibiotic susceptibility was tested by disc diffusion method. RESULTS: Of 33 patients with A. sobria complex bacteremia, 66.7% were men and 72.0% were older than 50 years. Most patients (72.7%) had community-acquired infection. The commonest associated conditions were liver cirrhosis (42.4%) and neoplasm (30.3%). With the exception of diarrhea, the clinical manifestations were similar to those of other Aeromonas spp. Secondary bacteremia occurred in 51.5% of patients, most of whom had either biliary tract infection (47%) or peritonitis (23.5%) as the major infection focus. Monomicrobial bacteremia was recorded in 23 patients. All isolates were susceptible to gentamicin, amikacin, ceftazidime, cefepime, and ciprofloxacin; 90.9% were susceptible to aztreonam and piperacillin-tazobactam, 87.9% to imipenem, and 78.8% to trimethoprim-sulfamethoxazole. The mortality rate was 39.4% and nearly 50% of deaths occurred within 96 h of admission. Hypotension, impaired renal function, and liver cirrhosis were significantly associated with a high mortality rate. CONCLUSIONS: A. sobria complex bacteremia usually occurs in patients with liver cirrhosis or neoplasm. In patients with A. sobria complex bacteremia, a secondary infection focus should be considered. Adequate antibiotics should be given early, especially to patients with hypotension and impaired renal function.