Sinus bradycardia may be seen commonly in healthy individuals and athletes without any significance. It may also occur in cardiovascular and systemic diseases. Sinus bradycardia is a common clinical sign in patients with anorexia nervosa. However, it is not usual to experience a patient with severe bradycardia who was diagnosed to have anorexia nervosa after being treated with a permanent pacemaker. We presented a 16-year-old, sportive boy who was initially admitted to the Department of Paediatric Cardiology with severe bradycardia, treated with permanent cardiac pacemaker and then diagnosed with anorexia nervosa. As per this case, physicians should consider anorexia nervosa in the aetiology of severe bradycardia, especially in young patients on excessive exercise and dieting, and refer these patients to the mental health professionals.