This review summarises the current knowledge of electroconvulsive therapy (ECT) which is still the most potent and fast-acting antidepressant intervention. The modern procedure is safe when general precautions are taken. Cognitive side effects are transient in most patients, and concerns about side effects should not prevent relevant use. Due to the prognostic benefits of rapid remission, ECT should, in relevant patients, be considered early in the treatment course. Patients should be offered maintenance pharmacotherapy, and, in high-risk cases, tapering of the acute ECT course or maintenance ECT, in order to reduce the risk of relapse.