In a group of patients with complete atrioventricular block admitted for implantation of a cardiac stimulant, 15 out of 74 patients (20.3%) had normal intraventricular conduction before the block, while 59 (79.7%) had disorders of intraventricular conduction. A combination of right bundle-branch block with block of the anterior limb of the left branch was the most frequent occurrence (37.8%). Comparison of the QRS complexes in maintained atrioventricular conduction with those in complete antrioventricular block showed that among patients with disorders of intraventricular conduction complete atrioventricular block was of a proximal character in 45.5% and of a distal character in 54.5% of cases. There was a high risk of development of complete atrioventricular block in patients with right bundle-branch block combined with block of the anterior limb of the left branch; it was found to be 41.2% at an average follow-up period of 23 months.