Of 1484 pacemakers placed at our institution between 1970 and 1980, there were 18 patients between the ages 20 and 40 years who were not postoperative congenital heart disease cases. Twelve of these patients had primary sick sinus syndrome (SSS) as the indication for pacing. Eleven of 12 patients were markedly symptomatic with syncope, near syncope, or lightheadedness. Ambulatory monitoring revealed evidence of sinus node disease in all patients studied. Electrophysiologic studies were falsely negative in the five patients in whom they were performed. Patients tolerated pacemaker therapy well and became asymptomatic with pacing. We conclude that SSS in young adults is uncommon, but still represents the most common indication for permanent pacemaker therapy in this age group. The decision for pacemaker therapy should depend on symptoms and results of ambulatory monitoring. These patients can expect symptomatic improvement with pacing.