Background: Isolated complete atrioventricular block is a rare disease often associated with maternal autoantibodies. This study aimed to present the mid-term data of patients at our clinic diagnosed with isolated complete atrioventricular block. Methods: We evaluated 108 patients diagnosed with isolated complete atrioventricu-lar block. Demographic data of the patients, electrocardiography, echocardiography, 24-hour Holter monitoring data, and follow-up and complications of the patients who underwent pacemaker implantation were evaluated retrospectively. Results: The mean age of the patients at diagnosis was 5.51 +/- 5.05 years. At the time of diagnosis, 74.8% of the patients had no symptoms associated with complete atrioven-tricular block. The most common symptom was fatigue. Pacemaker implantation was needed in 88 (81.4%) patients during follow-up. Significant bradycardia was the most common pacemaker implantation indication. The mean battery life was 5.41 +/- 2.65 years. The battery replacement-free period of 68 patients who underwent pacemaker implan-tation and continued their follow-up was 4.18 +/- 2.89 (0.1-10) years. Pacemaker-related complications developed in 8 patients during follow-up. Left ventricular dysfunction developed (dyssynchrony induced) in 3 patients at follow-up, and all were paced from the right ventricular anterior wall. Those patients underwent cardiac resynchronization therapy and their left ventricular dysfunction improved. Conclusion: Isolated complete atrioventricular block is a rare disease requiring care-ful clinical follow-up. Patients are often asymptomatic and significant bradycardia is the most common indication for pacemaker implantation. Left ventricular dysfunction is an important cause of morbidity, especially in patients with right ventricular anterior wall pacing. Physicians should be aware of left ventricular dysfunction during follow-up. Cardiac resynchronization therapy should be considered as a treatment option for left ventricular dysfunction.