The electrocardiographic changes produced at surgery in all patients undergoing total correction of tetralogy of Fallot at the Seoul National University Hospital from 1961 through August 1979, were reviewed. Particular attention was directed to the presence of postoperative right bundle branch block combined with left anterior hemiblock and its prognosis. 14 patients [9.4%] out of 149 who were survived for 30 days postoperatively, showed right bundle branch block with left anterior hemiblock pattern in electrocardiography. But no complete heart block was occurred in these l 4 patients during the follow up periods of 2-56 months.[KTCS 1979;4:336-338]