Abstract
Fifty-nine (42%) of 140 schizophrenic patients taking phenothiazines were found to have abnormal electrocardiograms. The abnormalities included T wave changes, S-T depression, P-R and Q-T prolongation, persistent sinus tachycardia (110 or more/min) and right bundle branch block. In forty-eight (34%) of the fifty-nine patients, the ECG abnormalities disappeared after stopping the phenothiazine and reappeared on its resumption.