To evaluate whether lithium treatment has been overvalued and may be no longer as effective as formerly, we reviewed published reports on long-term lithium treatment (1970-1996) as well as analyzing its clinical effects on 360 patients with DSM-IV bipolar disorder who entered into lithium maintenance monotherapy after 1970. Neither reported recurrence rates nor average proportions of time ill nor patient improvement of 50% or more during lithium maintenance therapy in a stable clinic setting has changed significantly since the 1970s. Unfavorable results in some settings may reflect accumulation over time of patients with complex, less treatment-responsive illnesses. Lithium is unmatched in research support for long-term clinical effectiveness against morbidity and mortality associated with depression or mania in bipolar I and II disorders. Data evaluated herein did not support suggestions that benefits of lithium have been exaggerated in the past or have been lost recently.