disease is a multisystemic disease caused by Borrelia species, and it is transmitted to humans by ticks of the species Ixodes. There are three genotypes of the Lyme disease agent: Borrelia burgdorferi sensu stricto, Borrelia garinii, and Borrelia afzelii. They are grouped together under the name B. burgdorferi sensu lato (1). The causative agent of Lyme disease, B. burgdorferi, was isolated in 1982 (2). Lyme disease is evident in three stages. The first stage includes erythema migrans (EM) and needs no serological testing. Diagnosis becomes more difficult in the second and third stages. In such cases, two-step diagnosis is necessary. The first step is based on an enzymelinked immunosorbent assay (ELISA) test, and positive results should be confirmed by Western blot (WB) (3). Cross-reactions have been found between antibodies to syphilis, leptospirosis, relapsing fever, varicella, infectious mononucleosis, and some autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis), and ELISA tests may provide false positive results so the results should be confirmed by WB (4). This disease is a common tick-borne zoonosis in European countries and the United States. In Turkey, the first cases were reported in 1990 in the Black Sea and Aegean regions (1). Because Lyme disease is not a compulsory notification disease in Turkey and due to confusion with clinical signs of other diseases, the exact prevalence is not known.In the present study, the aim was to determine the seroprevalence of Borrelia burgdorferi sensu lato in the city center and the province of Bolu, Turkey.