To study outcome in manic patients treated under routine clinical conditions, 73 manic and 66 unipolar depressed patients were followed up 1.7 years after hospitalization. A surprisingly large percentage of manic patients showed difficulty in post-hospital adjustment, and over 40% experienced a manic syndrome during the follow-up period. Manic patients showed poorer outcomes than did unipolar depressives. Manic patients taking lithium carbonate did not show better outcome than those not taking lithium carbonate. The results suggest (1) many hospitalized manic patients have a severe, recurrent, and pernicious disorder; and (2) in routine clinical practice, lithium carbonate treatment is an effective prophylaxis for fewer than the 70% to 80% of manic patients previously reported.