The higher complication rate with atrial than ventricular leads make the physiological mode of pacing less popular. The aim of this study was to assess the complications associated with atrial leads. Between July 1985 and December 1991 we inserted 174 atrial leads in 165 patients (pts) with sick sinus syndrome or/and a-v block (AAI and DDD system respectively). A variety of different types of unipolar leads have been used: passive fixation simple or J shaped with the porous tip of vitreus-carbon (n = 49) and platinum-iridium (n = 78) or polished tip of Elgiloy (n = 18), active fixation (n = 29). The leads were manufactured by Siemens-Elema, CPI, Biotronik, Medtronic and Vitatron. All leads have similar acute electrical characteristics. The mean follow-up period lasted 28 months (12-83) until June 1992. We observed the following complications: displacement of electrode tip in 16 pts (9.7%), the disturbances of sensing in 10 pts (6%), 3rd degree of a-v block in 6 pts (5.4%) of 111 pts with AAI pacing, the exit-block in 3 pts (1.8%), suppuration in 3 pts (1.8%) in pacemaker area, various in 1 pt (0.6%). Total complication rate, which required reoperation was 20.6%. Complications associated with atrial leads implantation are not dangerous, may be easily treated and should not limit the indication for physiological pacing.