DNA probes specific forCampylobacterjejuni have been developed. A genomic library ofC. jejuniwas constructed and screened with32P‐labeled genomic DNA fromC. jejuniandC. coliby colony hybridization. Several clones that reacted only withC. jejunibut not withC. coliwere selected. Two DNA inserts (1.5 kb and 0.8 kb) were isolated from the positive clones. A modified Southern hybridization technique indicated that these two32P‐labeled DNA inserts were specific forC. jejuni.the 1.5 kb DNA insert was partly sequenced, and a 19 base oligomer probe was selected from the sequences. Southern hybridization indicated that the oligomer probe hybridized with DNA from all seven strains ofC. jejunitested bus did not hybridize with DNA from four strains ofC. coli, one strain ofC. fetusandC. laridis, or 11 other bacterial species tes