Pacemaker malfunctions are secondary to alterations of the preset pacing rate, irregular pacing failure of sensing, failure of cardiac capture or depolarization, and various combinations of these events. A 76 years old male patients was admitted due to pacemaker malfunction. 2 years ago, he was diagnosed as complete atrioventricular block. And then bipolar permanent pacemaker was implanted. Since then syncopal attack developed repetitivly. 12 lead ECG and 24 hour holter moniter monitoring, revealed pacing and sensing failure, thus we converted bipolar system into unipolar system. since then syncopal attack did not developed again.