Complete congenital heart block has been recognized since 1846, yet the prognosis of the disease has not been determined by comprehensive long-term studies. We reviewed 14 cases of complete congenital heart block at The Cleveland Clinic Foundation. The patients were followed for a mean of 25 years (range, 20 to 32 years). Ten patients had structurally normal hearts, and 4 had varying degrees of congenital heart disease. The patients were evaluated with regard to symptoms, and indications for permanent pacemaker implantation were studied. Seven patients received permanent pacemakers. Ages at the time of pacemaker implantation ranged from 15 to 38 years (mean, 25 years). Overall, the patients in our study tended to lead normal productive lives. The main indications for pacemaker implantation were symptoms alone. Guidelines for prophylactic pacemaker implantation have yet to be determined, and the development of these guidelines is difficult due to small numbers of patients at isolated centers. A large international study is needed to set these guidelines.