In order to determine whether electroconvulsive therapy (ECT) alters left-ventricular function in patients without heart disease, we studied 11 patients who had a normal cardiovascular system and were submitted to ECT. Left-ventricular function was assessed by means of a clinical examination and an echocardiographic evaluation performed before the ECT and 20 min and 6 h after ECT. Twenty minutes after ECT, the patients’ end-systolic volume was increased (p = 0.003), whereas the ejection fraction (p = 0.004) and E to A ratio were decreased (p = 0.004 and 0.028, respectively). These indexes returned to the normal control value 6 h later. None of our patients presented any clinical signs of heart failure. We conclude that in some patients, ECT produces a significant and transient decrease in left-ventricular systolic and diastolic function.