Introduction: The incidence of generator exchange is being increased, as life expectancy of patients with a pacemaker is being prolonged. It is known that dual chamber pacing is more physiologic. However, there are some debates about outcome depending on mode of pacemaker. Methods: Population was 127 patients(62 짹 14.7 year-old, 39 males) whose generator was exchanged from 1992 to 2009. Retrospective review was done with reports of serial pacemaker analysis. Results: Initial left ventricular ejection fraction was 61.0 짹 8.3%. Thirteen among 127 patients were in heart failure of NYHA class III. Five AAI (3.2%), 58 VVI (46.8%), 13 VDD (11.3%) and 51 DDD (38.7%) were implanted initially. Sick sinus syndrome patients (n = 66) consisted of 30 VVI, 31 DDD, and 5 AAI. Complete AV block patients (n = 61) consisted of 28 VVI, 20 DDD, and 13 VDD. The causes of generator exchange were battery depletion (n = 105, 82.6%), capture or sensing failure (n = 17, 13.3%) and infection (n = 5, 3.9%). For 190 짹 47 months of follow-up, 16 patients were expired. The cause of death consisted of 5 malignancy, 3 heart failure, 3 sudden cardiac death, 1 diabetes complication, and four unknown causes. In sick sinus syndrome patients, there was no difference of survival between VVI and DDD (Kaplan-Meier, 226 vs. 211 months, p = 0.89). In complete AV block patients, there was no difference of survival between VVI and DDD (Kaplan-Meier, 212 vs. 180 months, p = 0.79). Left ventricular systolic dysfunction occurred earlier in VVI than DDD (176 vs. 239 months, p = 0.048). Conclusion: Generator depletion was the most common cause of generator exchange (72.6%). Long term mortality was not related with mode of the pacemaker. In complete AV block patients, left ventricular systolic dysfunction was less frequent in DDD mode than VVI mode.