Abstract: Nucleic acid probes are described for detecting bacteria capable of causing Lyme disease. These probes complement the ribosomal ribonucleic acid sequences unique to Borrelia spirochetes, and as such can detect the rRNA, rDNA, or polymerase chain reaction amplification products of these genes. These probes, plus the described amplification primers, can be used to detect the etiological agent of Lyme disease in human or veterinary samples, and for determining the infective potential of Ixodes ticks.