The "ideal" mood stabilizer has been defined as an agent displaying demonstrated efficacy for the acute treatment and long-term prevention of both mania and depression. On the basis of a selective and an extensive review of the existing literature primarily focused on prospective and controlled studies, we discuss the potential mood-stabilizing effects of electroconvulsive therapy (ECT) and its efficacy for the acute treatment of bipolar depressive and mixed-manic states and the prevention of all types of recurrences of bipolar disorder (BD). We conclude that ECT should be considered an effective acute treatment for the depressive and manic-mixed states of BD, as ECT displays response and remission rates superior to those of other treatment approaches, even in severe and treatment-resistant cases. From this point of view, its clinical mood-stabilizing effects are clearly superior compared with other pharmacological approaches because most treatments that alleviate bipolar depression can cause mania, hypomania, mood instability, or rapid cycling and treatments that can control mania can induce or precipitate depressive symptoms or episodes. The ECT-induced mania is rare, and there are no data suggesting possible long-term mood destabilization, including cycle induction or acceleration. Conversely, several case reports and open trials reported a significant reduction in morbidity among patients experiencing rapid-cycling BD. Regarding relapse prevention, c-ECT and m-ECT are considered as appropriate therapies for treatment-resistant patients exhibiting high rates of depressive or mixed relapse. Further investigation is necessary to identify the frequency and duration of continued treatment after a successful index course of ECT.