Electroconvulsive therapy (ECT) is a highly effective treatment for major depression. New ECT devices with shorter pulse widths seem to induce seizures more effectively at a lower seizure threshold and with fewer cognitive adverse effects. Suprathreshold right unilateral (RUL) ultrabrief-pulse ECT with pulse widths between 0.25 and 0.30 millisecond seem to be especially effective with regard to efficacy and cognitive adverse effects. A lower pulse frequency (50 pulses per second) in RUL ECT was found to be more efficient than a higher pulse frequency (200 pulses per second) in inducing seizures. However, effective stimulus dose can often be achieved only with high stimulus frequency, whereas the impact of increased stimulus frequency on antidepressant efficacy and cognitive adverse effects is not known.