We reviewed 75 episodes of Aeromonas spp. bacteraemia observed at our institution in 1979-2002, with special reference to episodes occurring in elderly patients (> or = 65 y) and to nosocomial episodes. In addition, we compared monomicrobial bacteraemic episodes caused by Aeromonas spp. (n = 54) with those caused by Escherichia coli (n = 108) and Pseudomonas aeruginosa (n = 108), to assess differences in clinical presentation and outcome. The 75 episodes of Aeromonas spp. bacteraemia occurred mainly in males (72%), suffering from chronic liver disease (36%) or neoplasm (33%). They had an abdominal origin in 52% of cases, were recorded as primary bacteraemia in 40%, and showed a 30-d case fatality rate of 36%. 22 episodes (29%) were nosocomial, 36 (48%) occurred in elderly patients and 21 (28%) were polymicrobial infections. In comparison with Aeromonas spp., E. coli bacteraemia was more often associated with less severe underlying conditions, a community-acquired infection (74%), and a urinary tract (52%) or abdominal (27%) origin and had a 30-d case fatality rate of 24%. P. aeruginosa bacteraemia occurred mainly in patients with severe underlying conditions, was associated with nosocomial infection (69%), and had a 30-d case fatality rate of 43%. In conclusion, Aeromonas spp. bacteraemia is a serious infection that should be considered in patients with chronic liver disease or neoplasm. It may occur in the elderly and as a nosocomial infection, and differs in clinical findings from bacteraemia due to other common pathogens.