It has been suggested that unilateral electroconvulsive therapy (ECT) is less effective than bilateral ECT in manic patients. In a pilot study, six medication-resistant manic patients received either left or right unilateral ECT. In an ongoing study, 14 similar patients were randomly assigned to receive left unilateral, right unilateral, or bilateral ECT. Across both studies, a therapeutic equivalence for unilateral and bilateral ECT was found. Possible reasons for disparate findings with respect to the efficacy of unilateral ECT in mania are discussed.