The interest in VDD pacemakers has been renewed by the introduction of single-pass leads, and continuing modifications and technical developments promise significant improvement. However, convincing long-term data confirming the reliability and the use of newer leads are not yet available. Compared with VVIR pacemakers VDD pacing has theoretical advantages over the VVIR mode, offering better hemodynamic and endocrine responses. However, its range of indications is narrow and rate adaptation is essential when sinus node chronotropic inadequacy is present or likely to occur. In addition, on certain occasions a VDD pacemaker may not maintain persistent atrial-synchronous pacing, thus necessitating the use of a DDD unit.