Implantable pacemakers are being employed with increasing frequency in the management of patients with bradycardia. Improvement in the design and manufacture of impulse generators and electrodes has increased their reliability and general acceptance. Development of newer types of pacemakers, atrial and ventricular, synchronous as well as demand units, has broadened the selection available for implantation. Perfection of the endocardial electrode has made it feasible to offer this mode of treatment to more patients. These events have modified the management of patients with bradycardia, most notably in the criteria for selection of both the patients and the method of treatment. This report presents our experience with the use of implantable pacemakers during a period of more than seven years. Material From March 1961 to November 1968 we have treated 101 patients with bradycardia by pacemaker implantation. Some of these patients have been reported previously.1 Mean age in this group was