Monitoring of pacemaker patients is usually performed by 24 hour-long-term-ECG or event recorder. The newer pacemaker generation offers a variety of diagnostic features such as histograms, event counters of sensed or paced beats, trends of periodically measured lead impedance and amplitudes of sensed beats as well as automatic measurements of ventricular threshold. Predefined episodes of atrial and ventricular tachyarryhthmias can be documented as intracardiac electrogrammes and validated during pacemaker follow-up, thus leading to therapeutic consequences. Patient-triggered episodes can proove or exclude arrhythmogenic events. Special algorithms try to suppress the occurence of paroxysmal atrial fibrillation, newest pacemaker systems are even able to terminate atrial tachyarryhthmias by rapid atrial overdrive stimulation. Diagnostic and therapeutic options of modern antibradycardic pacemakers offer a permanent implanted rhythm-monitoring and try to reduce the incidence of atrial tachyarrhythmias.