Electroconvulsive therapy (ECT) is a highly effective treatment for MDD that is helpful for patients with the most severe forms of affective illness; however, relapse after successful acute phase ECT or pharmacotherapy remains a major public health problem. To prevent relapse in patients with MDD who have responded to ECT, the common practice is to prescribe an antidepressant (e.g., a tricyclic [TCA], a selective serotonin reuptake inhibitor [SSRI], or lithium) as continuation therapy. Recent studies show an alarmingly high relapse rate after ECT despite conventional continuation pharmacotherapy (C-PHARM). Continuation ECT (C-ECT) is also in widespread clinical use; however, its efficacy and safety have never been rigorously tested.