A consecutive series of 18 patients (5 males, 13 females, mean age +/- DS 65 +/- 12 and 66 +/- 13 years, respectively, and mean +/- DS Wenckebach point of 162 +/- 20 ppm) given arterial pacemakers for sinus node dysfunction (SND) were followed to study the incidence of lead failure, atrioventricular conduction disturbances and chronic atrial tachyarrhythmias. The mean follow up time +/- SD was 18 +/- 10 months. There was not lead dislodgement. Chronic voltage output was reduced to 2.5 volts in 73% of patients because of a reduced chronic pacing threshold. One patient presented acute transient rise of pacing threshold and temporary loss of atrial detection. Progression to AV block was not documented. One patient had asymptomatic Wenckebach AV block during the night while on digoxin plus amiodarone. The AV block disappeared after cessation of drug therapy. Patients with previous episodes of paroxysmal atrial fibrillation did not presented the arrhythmia during follow up, while 75% of patients with previous atrial flutter presented the arrhythmia. None of the patients had systemic embolism. In conclusion, AAI pacing is a reliable and safe mode of pacing in patients with SND.