Background: The frequency with which stools contain Shiga-like toxin producing Escherichia coli not belonging to serotype 0157:H7 is unknown in the United States. The aim of this study was to determine the frequency with which these E. coli are present in stools from children from Seattle submitted for bacteriologic analysis. Methods: 2225 coliform colonics from 445 stools submitted for bacterial culture from Seattle children were probed with the structural genes of Shigalike toxins I and II in a 1-year prospective study. The adherence and actin aggregating characteristics of these E. coli were subsequently determined. Results: Five (1.1%) patients had non-0157:H7 Shiga-like toxin producing E. coli, a rate of isolation higher than Shigella or Yersinia (0.2% each) but lower than Campylobacter (2.5%), E. coli 0157:H7 (2.9%), or Salmonella (3.4%). Only one of the five patients had bloody diarrhea. None developed hemolytic uremic syndrome. All strains adhered in a localized pattern to, and induced actin aggregation in, HeLa cells, and produced a toxin that was lethal to Vero cells. Conclusions: Non-0157:H7 Shiga-like toxin producing E. coli are present in stools submitted for bacterial culture in a North American childhood population. Their role in childhood diarrhea warrants better definition.