Haemolytic-uraemic syndrome (HUS) associated with Aeromonas hydrophila enterocolitis is reported in a 23-month-old female infant. The A. hydrophila strain isolated from the patient's stool sample produced cytotoxin against verocells; increasing levels of cytotoxin-neutralizing antibody in the patient's sera were demonstrated, suggesting a recent infection. This report indicates that A. hydrophila should be suspected as a possible cause of HUS, and that this pathogen should be looked for in cases of post-diarrhoeal HUS.