BACKGROUND Lyme disease is the most frequent tick-borne infectious disease in Europe. The discovery of the causative pathogen Borrelia burgdorferi in 1982 opened the way for the firm diagnosis of diseases in several clinical disciplines and for causal antibiotic therapy. At the same time, speculation regarding links between Borrelia infection and a variety of nonspecific symptoms and disorders resulted in overdiagnosis and overtreatment of suspected Lyme disease. METHOD The authors conducted a selective review of the literature, including various national and international guidelines. RESULTS The spirochete Borrelia burgdorferi sensu lato is present in approximately 5% to 35% of sheep ticks (Ixodes ricinus) in Germany, depending on the region. In contrast to North America, different genospecies are found in Europe. The most frequent clinical manifestation of Borrelia infection is erythema migrans, followed by neuroborreliosis, arthritis, acrodermatitis chronica atrophicans, and lymphocytosis benigna cutis. Diagnosis is made on the basis of the clinical symptoms, and in stages II and III by detection of Borrelia-specific antibodies. In adults erythema migrans is treated with doxycycline, in children with amoxicillin. The standard treatment of neuroborreliosis is third-generation cephalosporins. CONCLUSIONS After appropriate antibiotic therapy, the outcome is favorable. In approximately 95% of cases neuroborreliosis is cured without long-term sequelae. When chronic borreliosis is suspected, other potential causes of the clinical syndrome must be painstakingly excluded.