Thirty-four hospitalized manic patients were randomized to treatment with either lithium carbonate or an average series of nine bilateral electroconvulsive treatments (ECTs), followed by maintenance with lithium carbonate. Weekly ratings of manic, depressive, and psychotic symptoms were obtained for eight weeks, and patients were followed up monthly for up to two years. Ratings by nonblind and blind observers indicated that the patients who underwent ECT improved more during the first eight weeks than did patients who were treated with lithium carbonate. This was especially true of patients with mixed symptoms of mania and depression and/or extreme manic behavior. Clinical ratings after eight weeks showed no significant differences between the lithium carbonate- and ECT-treated patients. Likewise, the two groups had comparable rates of relapse, recurrence, and rehospitalization during the follow-up period.