Lyme disease is an emerging infection caused by the spirochete Borrelia burgdorferi. It is the most common vector-borne disease in the USA and Europe, and it is transmitted to humans through the bite of ticks of the genus Ixodes. Its animal reservoirs are the white-tailed deer, the white-footed mouse, and other small mammals. It is considered the new "great imitator", with its diagnosis being a major challenge. Traditionally it is divided into four stages, early localized disease, early disseminated, late disease, and the post-Lyme syndrome. Clinical manifestations may be both cutaneous and systemic, and can have cardiovascular, neurological, and musculoskeletal involvement. Diagnosis is based on clinical findings and can be confirmed by serologic studies (ELISA and Western Blot). The best preventive method is to avoid exposure to vectors. The aim of treatment with antibiotics (doxycycline and cephalosporins) is to relieve symptoms and prevent sequelae.