The effect of thiopental and sevoflurane (1 MAC, 2 MAC) on hemodynamics was assessed in a randomized study involving 38 adult patients undergoing electroconvulsive therapy (ECT). Blood pressure, heart rate and electrocardiogram (ECG) were monitored during the ECT procedure. After oxygenation, hypnosis was induced with a bolus injection of thiopenal (TPS) 4 mg.kg-1. Muscle relaxation was achieved by succinylcholine, 1 mg.kg-1 intravenously before ECT procedure. Ventilation was assisted using a face mask with 100% oxygen (TPS group), 1.7% sevoflurane (1 MAC group) or 3.4% sevoflurane (2 MAC group), plus 50% nitrous oxide and 50% oxygen. Thereafter, an electrical stimulus was administered. A total of 150 treatment sessions were evaluated. The rate pressure product increased in every group right after ECT, but the use of sevoflurane (2 MAC) significantly diminished the response compared with sevoflurane (1 MAC) and thiopental. In the sevoflurane (2 MAC) group, no ventricular arrhythmias were observed. In general, it seems that sevoflurane (2 MAC) is as effective as thiopental and sevoflurane (1 MAC) as an induction agent for ECT.