This is a case of a 13-year-old male with frequent premature ventricular contractions with QRS configurations of the left superior axis and left bundle branch block, which originated from the posterior–superior process of the left ventricle. Premature ventricular contractions were successfully eliminated by delivering radiofrequency energy to the inferior wall of the right atrium without causing either junctional rhythm or atrioventricular block. Ventricular arrhythmias originating from this site have been sporadically reported in adults; however, this is the first report in a child.