Among a series of consecutive patients treated with permanent pacemaker between 1965 and 1976, 43 had sinoatrial disease with paroxysmal tachycardia (group A), 30 sinoatrial disease without tachycardia (group B) and 165 atrioventricular block (group C). A retrospective study showed systemic vascular events compatible with embolism in 35%, 7% and 10% in groups A, B and C, respectively. The groups were comparable as regards age, other diseases and duration of pacemaker therapy. Because of the high incidence of embolism in group A, anticoagulant therapy should be evaluated in patients with the brady-tachycardia syndrome.