A total of 209 well-defined Campylobacter, Helicobacter, and Wolinella strains were tested with a Gen-Probe oligodeoxyribonucleotide probe for Campylobacter jejuni, Campylobacter coli, and Campylobacter lari. Released ribosomal RNA was hybridized with the acridinium-ester-labeled probe. The amount of light proportional to the number of DNA-RNA hybrid molecules was captured by a photo-multiplier and converted to a digital signal. A reading of more than 50,000 relative light units (RLU) was considered positive. After isolates were cultivated, lysis and hybridization procedures were completed in 30 minutes. All 104 strains within the target species were positive, as well as two Campylobacter hyointestinalis strains. The remaining 103 strains, including 15 C hyointestinalis strains, were negative. Our data indicate a sensitivity of 1.0 and specificity of 0.98 (P <.001).