We report a case of complete atrioventricular (AV) block in a 40-year-old patient with Duchenne muscular dystrophy (DMD). While he was bed-ridden and required mechanical ventilation, his cardiac involvement was mild. He had the deletion of exon 45-52 in the dystrophin gene. He underwent transient complete AV block and came to require pacemaker implantation due to recurrence of complete AV block ten days after the first attack. Electrophysiological study revealed mild prolonged AH and HV interval. Although DMD patients with AV block have been rarely reported so far, attention should be paid to AV block for patients who prolonged their lives.