Persistent left superior vena cava (PLSVC) is a rare but one of the most common venous anomalies. Its incidence is reported as 0.3 - 0.5% in the general population, but in those with congenital heart disease, its incidence may range as high as 3 - 10%. PLSVC draining into coronary sinus is usually of little hemodynamic consequences, but it may become significant during cardiac catheterization, transvenous pacemaker insertion and cardiac surgery. Some investigators suggested that this anomaly is related with cardiac electrical instability due to anomalous development of AV nodal tissue with venous draining anomaly, and others suggested that the predisposing anomaly is in the sinus node and the dysrrhythmia is part of sick sinus syndrome. We report a 48 year-old female who had intermittent palpitation and near syncope, was diagnosed as sick sinus syndrome and underwent to implant permanent dual pacemaker implantation. Before implantation, we suspected PLSVC in 2-dimensional and contrast echocardiogram and confirmed it by cardiac catheterization. So, we successfully performed pacemaker implantation via right subclavian approach.