Electroconvulsive Therapy (ECT) involves the induction of a convulsion (seizure) by the application of electrical current to the brain. The stimulus parameters are: current (usually 500 to 800 mA); frequency (20 to 120 Hz); pulse width (0.25 to 2 ms) and duration (0.5 to 8 or more seconds). ECT is typically delivered two or three times per week under monitored conditions. There is consistent evidence that the antidepressant efficacy of ECT is related to its stimulation parameters. Bitemporal placement is generally regarded as faster in improving depressive symptoms and more effective than unilateral, at a lower dose of electrical stimulus. However, bitemporal placement is associated with more cognitive side effects (Stoppe et al., 2006). When ECT is prescribed as a first-line treatment (Table 4) or in individuals with a history of antidepressant medication trials of inadequate dose or duration, response rates in the 80% – 90% range have been reported (Petrides et al., 2001). In most countries the use of ECT is reserved for a major depressive episode that has proved “treatment resistant” to adequate trials of two or more pharmacotherapies, including combination medications and/or cognitive therapy. When used in patients who have failed to respond to one or more adequate antidepressant medication trials, ECT response rates have traditionally been estimated to be 50 – 60% (Prudic et al., 1996).