These cases illustrate that late stage Lyme borreliosis can occur in children without a history of tick bite or ECM; this disorder can manifest itself initially as a seventh cranial nerve palsy, heart block, or arthritis, and the arthritis syndrome can mimic oligoarticular juvenile rheumatoid arthritis. The diagnosis of Lyme borreliosis depends upon clinical recognition. In the absence of ECM, tests for antibodies to Borrelia burgdorferi can provide an invaluable tool in assisting in the diagnosis. Children who live in or visit areas endemic for Lyme borreliosis and who have arthritis, heart block, or neurologic disorders such as facial palsy should be tested for antibodies to Borrelia burgdorferi if no other cause for the disease syndrome is identified clinically.