To investigate the pathogenic role of enteroaggregative Escherichia coli (EAggEC) among human immunodeficiency virus-infected persons, 111 outpatients with and 68 without diarrhea were evaluated. Examination of stool samples included the HeLa cell adherence assay and an EAggEC polymerase chain reaction (PCR) assay using primers complementary for the plasmid locus CVD432. The pCVD432 genotype, adherence phenotype, and patient characteristics were correlated with occurrence of diarrhea by multivariate analyses. EAggEC PCR and adherence assays were positive in 7 (6%) and 24 (22%) patients with diarrhea and in 1 (1%) and 21 (31%) asymptomatic control patients, respectively. Clinical manifestations associated with EAggEC PCR-positive isolates were nonspecific; EAggEC infections were independent of CD4 lymphocyte counts. Of the pCVD432 genotype, 5 (71%) of 7 were resistant to cotrimoxazole and ampicillin, and 1 strain was resistant to ciprofloxacin. Overall, pCVD432 PCR-positive E. coli was the most prevalent intestinal organism associated with diarrhea. The adherence assay results did not correlate with diarrhea.