131 patients received permanent pacemakers to treat their hypersensitive carotis sinus syndrome (HCSS). Prior to implantation, HCSS was diagnosed whenever spontaneous episodes of faintness or dizziness (n = 25) or syncope (n = 106) coincided with an abnormal response to carotis sinus massage (asystole greater than 3 s). 123 patients were followed for 48 +/- 27 months after implantation to assess the value of pacemaker therapy. 77% of all patients were free of initial symptoms. 90% of patients with syncope prior to pacemaker therapy were free of recurrence. Therefore, permanent pacing appears to be the treatment of choice for these patients. Since carotis sinus massage produced high-degree AV-block in at least 33% of patients, ventricular (rather than exclusive atrial) pacing seems to be mandatory. However, syncope did recur in 10% despite normal pacemaker function. The etiology of these recurrences remained unclear in almost all patients. As opposed to patients with syncope, cardiac pacing prevented symptoms in only 26% of patients with faintness or dizziness without full syncope. In these patients primary and sole pacemaker therapy does not appear to be appropriate.