We reviewed evidence of a possible antisuicide action of lithium maintenance treatment in mood disorders. Of 28 published studies involving over 17,000 patients with major affective illnesses, most yielded supportive evidence: risk of suicides and attempts averaged 3.2 versus 0.37 per 100 patient-years without versus with lithium (8.6-fold difference). In a new study of 284 bipolar I- and II-disordered patients, corresponding rates (2.2 vs. 0.39/100 patient-years) differed by 5.6-fold (p < 0.001); moreover, after discontinuing lithium, rates of suicidal acts rose by 7-fold (16-fold within the first year), and fatalities increased by nearly 9-fold. Lithium maintenance treatment in recurring major mood disorders has strong evidence of antisuicide effects not demonstrated with any other mood stabilizer. Close association of suicide and depression in bipolar disorder emphasizes the need for improved identification and treatment of bipolar depression.