An examination of 632 consecutive pacemaker implantations performed at a single institution by 29 implanting physicians over a 5 year period was made to determine which factors affected the 37 perioperative complications experienced. The introducer method of vein access contributed significantly to the complication rate, which was also related to the number of physician implanters on the staff and the makeup of the implantation teams. Of greatest interest was the substantially large incidence of complications experienced by implanters who performed fewer than 12 implantations per year, and particularly the incidence of lead-related complications.