Clinical research centers in Aarhus, Berlin, Hamilton and Vienna collected mortality data for 827 manic-depressive and schizoaffective patients given lithium treatment for more than 6 months. The average duration of the treatment was 81 months and the total time on lithium 5600 patient-years. For each patient, the mortality risk was calculated by entering the appropriate national life tables for the general population. The number of observed deaths was 44; the number of expected deaths was 49.7. The standardized mortality ratio, 0.89, did not differ significantly from 1.0. The mortality of manic-depressive patients is 2-3 times that of the general population. Our data show that the mortality of manic-depressive and schizoaffective patients given long-term lithium treatment does not differ significantly from that of the general population.