Strains of Escherichia coli, hybridising with a DNA probe for enteroaggregative E. coli (EAggEC), were isolated from patients with infectious intestinal disease (IID) or gastro-enteritis, and healthy controls during the study of IID in England. Of 3506 cases presenting with an IID, 160 (4.6%) had faecal EAggEC as compared with 46 (1.7%) of 2772 healthy controls, 53% of EAggEC isolated from each of the 'case' and the 'control' groups adhered in a 'stacked-brick' formation. Strains from cases and controls belonged to over 39 and 14 different serogroups respectively, and approximately half of the strains isolated did not react with antisera in the current somatic antigen serotyping scheme. Forty-nine cases with EAggEC (31%) had a known history of foreign travel. Over 50% of strains isolated from cases and controls were resistant to one or more of eight antimicrobials, and antimicrobial resistance was not statistically significantly more common among cases with a known history of foreign travel (p = 0.57). These data form part of the largest investigation carried out on these organisms in the UK to date and provide the most comprehensive analysis of strains of EAggEC isolated from the general population of England.