Five hundred and eighty-nine consecutive transvenous pacemakers implanted between January 1, 1971 and January 1, 1985 were reviewed. A complication incidence of 17% early in the study period (1971-1977) was caused by electrode displacement and perforation. As of 1975, smaller-sized electrodes with endocardial fixation were used and were associated with a significant decrease in this complication incidence to 2% by 1985. All other complications occurring during the entire study period (1971-1985) occurred at a frequency of 3% (20/589). Infection occurred in 3 of 589 cases; there were no extrusions or erosions. No mortality was attributed to pacemaker insertion. The "twiddler" syndrome seems to be increasing in frequency. Transvenous permanent pacing can be accomplished today with a low complication rate of 5% or less. The majority of these complications are minor and can be corrected easily. Our studies suggest that the reduced complication incidence is mainly related to improved technology.