To assess the advantages and complications of a new universal (DDD) pacemaker, the initial 38 patients who received such a pacing device were studied retrospectively. This group consisted of 27 men and 11 women whose ages ranged from 23-89 yr. The pacemaker was the initial one for 32 patients and was the replacement unit for 6. Indications for dual-chamber pacing included a need to maintain atrioventricular synchrony, the previous occurrence of the pacemaker syndrome, or the presence of intact ventriculoatrial conduction and previous success with atrioventricular sequential pacing. Pacemaker-mediated tachycardia developed in 6 patients during the follow-up period. All 6 were successfully treated by a change in pacing mode. Eighteen pacemakers remained in the DDD mode, 17 were reprogrammed to the DVI mode and 3 were reprogrammed to the VVI mode. Seven patients experienced difficulties with loss of capture or undersensing, the most common problem being failure of atrial sensing. This was corrected in 4 of 5 patients by noninvasive reprogramming. Pacemaker-mediated tachycardia is a frequent complication that can be avoided by assessing ventriculoatrial conduction before implantation of the pacemaker. Use of the DDD device should be considered in patients in whom atrioventricular synchrony must be maintained or who have previously had the pacemaker syndrome with VVI pacing.