A 40-year-old man was referred to the cardiology outpatient clinic with dizziness, palpitations and shortness of breath. He remembered being bitten by a tick two to three years previously, but had not noticed a characteristic skin rash. The ECG showed a prominent first degree atrioventricular (AV) block and ambulatory electrocardiographic monitoring showed an intermittent complete AV block. A definitive pacemaker was implanted. Antibodies to Borrelia were found. The patient was treated with ceftriaxone. In the weeks and months following implantation, the AV block disappeared completely. The reversibility of the AV block secured the diagnosis 'Lyme carditis with secondary AV block', and the pacemaker was explanted.