Lyme disease, caused by spirochetes of the Borrelia burgdorferi sensu lato complex (hereinafter referred to as Lyme borrelia), is the most common tick-borne infection in the northern hemisphere (1). The potential for the infection to cause arthritis led to its recognition as a clinical entity in 1975 (2), and since then, the number of reported cases in the US and elsewhere has steadily increased. The Centers for Disease Control and Prevention (CDC) estimates that the annual incidence of Lyme disease in the US is 300,000, 10-fold more than the number reported by physicians. This review is intended to provide rheumatologists with a current understanding of Lyme disease in North America, with emphasis on arthritis pathogenesis and expected outcomes from treatment.