DNA homology determinations were used to classify atypical strains of Campylobacter spp. and Campylobacter-like organisms. Using the slot-blot hybridization technique, atypical strains were classified as C. coli or C. jejuni. Some of the Campylobacter-like organisms isolated from animals were catalase-positive, but they did not hybridize with the DNA probes prepared from the total genomic DNA of C. coli, C. jejuni, C. laridis, C. fetus subsp. fetus and C. hyointestinalis. The taxonomic classification of these strains remains uncertain. The slot-blot hybridization technique was simplified by applying whole cells from a 24 h broth culture, instead of pure DNA to nitrocellulose membranes. The results of DNA homology from both methods were comparable, and the classification of these organisms using these methods was the same. Therefore, the dot-blot hybridization method is recommended as a more economical and time-saving method for use in the taxonomic classification of atypical Campylobacter spp.