The paper presents the current state of knowledge on lithium treatment. The history of the therapeutic application of lithium began in 1859 and its introduction to modern psychiatry took place 90 years later. Since the early 1960s, lithium became a precursor of mood-stabilizing drugs and nowadays is the drug of choice for the prevention of manic and depressive recurrences in mood disorders. It remains a valuable drug for the treatment of acute episodes of mania and depression, especially for the augmentation of antidepressant drugs in treatment resistant depression. The factors of prophylactic efficacy of lithium in the context of the so-called excellent lithium responders and the efficacy in affective episodes were discussed. Among mood-stabilizing drugs, lithium exerts the biggest effect on preventing suicidal behaviors. It also shows antiviral (mainly against herpes viruses) and immunomodulatory activity. The evidence has recently been gathered on neuroprotective and ‛antidementia’ properties of lithium, which prompted its use in neurodegenerative disorders. The biochemical mechanism of lithium is associated mainly with the inhibition of glycogen synthase kinase-3 and an effect on intracellular signaling. The recommendations for managing lithium-induced adverse effects both in the early and late period of treatment as well as for lithium use in pregnancy and perinatal period were given. The necessity of overcoming negative perceptions of lithium was pointed out to increase the number of possible beneficiaries of lithium treatment. Both introduction of lithium into modern psychiatry and its therapeutic effects have been reflected in literature and art.