Genomic DNA from 12 different Campylobacter jejuni and 10 Campylobacter coli isolates was digested with SmaI and analyzed by pulsed-fieldgel electrophoresis(PFGE) and 16S rRNA hybridization studies. Although the two Campylobacter species displayed species-specific restriction and hybridization patterns, significant intraspecies differences were observed. Combined PFGE and hybridization pattern analysis failed to provide any more epidemiologic information than was obtained from PFGE restriction profiles alone. Therefore, results from these studies indicate that PFGE analysis of SmaI-restricted genomic DNA provides a reliable means of differentiating C.jejuni from C.coli and may represent a more practical approach to epidemiologic studies than combining conventional DNA restriction digestion patterns with RNA hybridization procedures.