We report a 5-year follow-up of eight patients implanted with the QT sensing rate adaptive pacemaker, the Vitatron TX. Careful programming was undertaken shortly after implantation utilizing repeated exercise testing to ensure optimal settings. Further exercise testing was not carried out during follow-up as the patients remained symptomatically well. Of six patients assessed with repeat exercise testing at 5 years, four demonstrated a satisfactory rate adaptive response with improved exercise performance compared to fixed rate ventricular pacing, one patient had an abrupt onset of increased pacing rate with exercise associated with improved exercise ability, and another developed an increased pacing rate after exercise but an appropriate rate adaptive response after reprogramming. One patient developed an inappropriately high pacing rate associated with congestive heart failure several months after a large myocardial infarction. One patient died from carcinoma. The QT sensing rate adaptive pacemaker appears to be reliable in lon-term clinical use when carefully programmed using exercise testing after implantation.