This article reviews the use of lithium from Roman times, when physicians first recommended alkaline springs in the treatment of mania, to the present. Serious interest in lithium began in 1949, with a report of improvement of mania in 10 of 10 patients. Since then, lithium has become increasingly popular both for treating acute mania and as a prophylactic agent. Its use in depression is also described. Finally, lithium's clinical spectrum is discussed, noting that its use extends far beyond the treatment of mania.