A 70-year-old man had annular erythema on the area extending from the right scapular region to the right axillary region, where he got tick bites on June 20, 1991. The erythema occurred soon after the bites and spread gradually to become as large as 20 square cm within 25 days. He also felt fatigue. An electrocardiogram revealed an atrioventiricular nodal block. We treated the patient with amoxycillin (750 mg daily) for 35 days. He has been now free from any symptoms over one year. Although repeated serological tests could not detect an antibody to Borrelia burgdorferi, typical erythema chronicum migrans and cardiac manifestation strongly suggested that the case could be diagnosed as Lyme disease.