Four strains of Escherichia coli O114:non-motile (NM) were isolated from patients supposed to have endemic diarrhea in 1989. The plasmid DNA profiles and restriction fragment patterns of chromosomal DNA digested with Not I analysed by pulsed-field gel electrophoresis (PFGE) of E. coli O114:NM strains were compared with those of other 9 strains of E. coli O114 isolated elsewhere (O114:H2, 1 strain; O114:H4, 2 strains; O114:H9, 2 strains; O114:H10, 1 strain; O114:H11, 1 strain; O114:H21, 1 strain; O114:H32, 1 strain). All of E. coli O114:NM strains showed the same plasmid DNA profile and chromosomal DNA fragment patterns. The strains of E. coli O114:NM and O114:H11, and O114:H21 and O114:H32 showed the same plasmid DNA profiles, respectively. On the other hand, these strains could be differentiated by the chromosomal DNA fingerprint patterns. The chromosomal DNA fragment pattern of all E. coli O114:NM strains is completely different from those of the other 9 control strains. We suggest that chromosomal DNA fingerprinting is useful for the epidemiological study of E. coli O114 associated endemic diarrhea.