Pacemaker dependency (PD) can be defined as the risk of serious injury or death from sudden pacemaker failure, an event more dangerous than progressive rate decrease. The aim of this study was to evaluate the incidence of PD during long-term follow-up after pacing system implantation.The study included 3638 patients (mean age 65.3 +/- 10.2 years). Indications for pacing were sick sinus syndrome (SSS) in 1315 patients, atrioventricular block (AVB) in 1482, AVB and SSS in 478 and atrial fibrillation (AF) with bradycardia in 363 patients. The mean follow-up was 4.8 +/- 1.8 years. Pacemaker dependency was defined as the absence of an intrinsic rhythm of 30 beats/min during back-up pacing and after switching off the pacemaker. If any significant symptoms of bradycardia developed or if the underlying rhythm did not appear (asystole > 5 s) the pacing was restarted. Pacemaker dependency was observed in 76 (2.1%) of the 3638 patients . In this subgroup pacing indications were SSS in 8 (0.6%) of 1315 patients, AVB in 52 (3.5%) of 1482, SSS and AVB in 15 (3.1%) of 478 and AF with bradycardia in 1 (0.3%) of 363. Patients with AVB had a significantly higher incidence of PD than patients with SSS or AF (p < 0.001, p < 0.005, respectively). A total of 139 patients suffered from myocardial infarction and 106 patients had a temporary pacing prior to pacemaker implantation. The majority of these patients were pacemaker dependent (p < 0.001).In our study PD occurred very rarely, being found in 2.1% of all patients. Patients with AVB have a significantly higher incidence of PD than patients with SSS or AF. Temporary pacing prior to pacemaker implantation and previous myocardial infarction indicate patients at risk of PD development. (Cardiol J 2007; 14: 83-86).