Lyme borreliosis is an infectious disease caused by Borrelia burgdorferi sensu lato spirochetes and is transmitted to humans by the bite of an infected tick from the Ixodidae family, e.g. Ixodes ricinus, Ixodes scapularis, Ixodes persulcatus. The same species are responsible for causing Lyme borreliosis: B. burgdorferi sensu stricto, B. afzelii, B. garinii, B. bissettii and B. spielmanii. The infection develops in stages and has various manifestations in the human body. Lyme disease mainly affects the skin, joints, the nervous system and the heart. Different species are bound with different clinical manifestations: Borrelia afzelii usually cause acrodermatitis chronica athrophicans, Borrelia burgdorferi sensu stricto is a common agent of arthritis, neuroborreliosis can be caused by B. burgdorferisensu stricto, B. afzelii and B. garinii. Lyme disease is diagnosed based on symptoms, epidemiological history and laboratory tests, e.g. serological tests of the serum or PCR tests from patient tissues or ticks. The most common diagnostic method is the one recommended by the Robert Koch Institute in Berlin. It is a two-stage procedure based on testing by screening assay in the first stage (EIA, IIFA, ELISA tests) and verifying positive and borderline results by Western blot tests during the second stage. Due to high antigenic variability, Borrelia burgdorferisensu lato spirochetes have an ability to avoid defence mechanisms of an infected organism. This is the main cause of problems with interpretation of the clinical symptoms, diagnostics results and also with treatment of this infection.