Lyme disease (Lyme borreliosis) is a systemic infectious disease that can present in a variety of clinical manifestations. The disease is caused by a group of spirochaetes--Borrelia burgdorferi sensu lato or Lyme borrelia--that are transmitted to humans by the bite of Ixodes ticks. Lyme disease is the most common arthropode-borne infectious disease in many European countries including Germany. Early localized infection is typically manifested by an erythema migrans skin lesion, in rarer cases as a borrelial lymphocytoma. The most common early disseminated manifestation is (early) neuroborreliosis. In adults, neuroborreliosis appears typically as meningoradiculoneuritis. Neuroborreliosis in children, however, is typically manifested by meningitis. In addition, multiple erythema migrans lesions and Lyme carditis occur relatively frequently. The most common manifestation oflate Lyme disease is Lyme arthritis. Early manifestations (and usually also late manifestations) of Lyme disease can be treated successfully by application of suitable antibacterial agents. For the treatment of Lyme disease, doxycycline, certain penicillins such as amoxicillin and some cephalosporins (ceftriaxone, cefotaxime, cefuroxime axetil) are recommended in current guidelines. A major challenge is the treatment of chronic, non-specific disorders, i. e., posttreatment Lyme disease syndrome and "chronic Lyme disease". Prevention of Lyme disease is mainly accomplished by protecting against tick bites. Prophylactic administration of doxycycline after tick bites is generally not recommended in Germany. There is no vaccine available for human beings.