We studied the clinical and epidemiological features associated with Aeromonas diarrhoea by a hospital survey of 7,398 children under 5 years of age presenting with diarrhoea. The data were actually based upon two cohorts from this survey, the majority of the data being identified from 405 (5.5%) in whom Aeromonas was the sole enteric pathogen. Aeromonas caviae was the most prevalent species, accounting for 32% (129/405) of all isolates. Eighty-three per cent of children with Aeromonas-associated diarrhoea were younger than 3 years. The majority of the children had acute onset of vomiting and watery diarrhoea resulting in mild to moderate dehydration. Fever, non-watery diarrhoea, age less than 3 years, and diarrhoea of 7-14 days duration were found to be significantly associated with Aeromonas diarrhoea compared with Vibrio cholerae O1 infection after adjusting for confounders. Aeromonas-associated diarrhoea was most common from March to May (during the peak of the hot and humid season), and September to October, similar to Vibrio cholerae O1. Our results indicate that Aeromonas infection is common in young children presenting with diarrhoea in Bangladesh.