By using HeLa cells, we tried to detect enteroaggregative Escherichia coli from stock strains derived from infants with or without diarrhea in Brazil and Myanmer, and from diarrheal patients in Osaka, Japan. Enteroaggregative E. coli was detected from 7.9% in diarrheal cases, 5.6% in control cases in Brazil and from 5.4% in diarrheal cases, 3.4% in control cases in Myanmar. A total of 38 strains that showed aggregative adherence to HeLa cells was examined for colony hybridization with the 32P-labeled EAggEC probe. Thirty-four strains hybridized with the EAggEC probe, while 4 strains did not hybridize with the probe, suggesting an existence of another aggregative factor. Seventeen of the 38 strains were O-antigen serotypeable. Eight strains belonged to serogroups O44, O86, O111, O125 and O126, which have been considered to be enteropathogenic E. coli serogroups. Most of the 38 strains were H-antigen serotypeable.