To determine the need for prophylactic temporary pacing in bifascicular block during surgical and other procedures, a retrospective analysis was carried out in 38 patients who underwent a total of 74 procedures. The male:female sex ratio was 3.2:1 and mean age was 74 (range 48-96) years. Known organic heart disease was absent in 45% of the total group. Patients were divided into four groups on the basis of their preoperative electrocardiograms. Of the 74 procedures, 19 were carried out under general, 22 under spinal and 29 under regional anesthesia; four endoscopic procedures were done without anesthesia. There was only one complication relating to deterioration of AV conduction. It is concluded that asymptomatic patients with right bundle branch block and left anterior hemiblock do not require prophylactic preoperative pacemaker insertion. Though experience is limited, the same may be true of patients with the additional finding of prolongation of PR interval.