Juvenile dermatomyositis (JDM) is characterized by proximal muscle weakness, vasculopathy of the skin and muscles, and typical skin rash. Approximately, 70% of adult patients with dermatomyositis have evidence of cardiac damage. However, cardiac involvement, one of the important causes of death, has been reported rarely in children with JDM. Here, we describe an 11-year-old boy who presented with bradycardia as a result of sinus node involvement due to JDM and recovered by the treatment of JDM without any specific drug for bradycardia.