Lyme borreliosis (LB) is a tick-borne infection caused by the spirochete Borrelia burgdorferi sensu lato. The disease covers a wide spectrum of clinical manifestations affecting the skin, nervous and musculoskeletal systems, the heart, and the eyes. The diagnosis must be based on clinical suspicion and on symptoms and signs observed during a thorough interview and examination of the patient. Laboratory results either support or oppose the conclusions that are drawn from history and clinical examination. Antibiotic therapy is curative in most patients with LB. Unfortunately, some patients develop chronic symptoms, such as arthritis, that do not respond to antibiotics. In these patients, treatment with non-steroidal anti-inflammatory drugs or corticosteroids is recommended, while the role of immunomodulatory drugs, such as tumour necrosis factor (TNF)-alpha inhibitors, remains open. In this review we focus, after presenting the history and basics of LB, on the pathogenesis, diagnosis, and treatment of LB, as well as on recent advances in selected aspects of the field.