For more than 30 years, lithium has been the drug of choice for the treatment of bipolar disorder. However, it has numerous adverse effects, a relatively slow onset of action, many common drug-drug interactions, and a narrow therapeutic index. Because of these problems, researchers looked for alternative and/or adjunctive treatments in bipolar disorder, focusing on the anticonvulsants carbamazepine and valproate. The existing data of valproate are reviewed pointing out its promises and limitations in psychiatric diseases. Growing data indicate that valproate is a well tolerated and effective agent in bipolar disorder. Controlled studies prove its use in acute mania, often with a rapid onset of action. Open studies suggest that the drug also reduces the frequency and intensity of recurrent manic and depressive episodes over extended periods. Its acute and prophylactic antidepressant effects are probably minor to its antimanic efficacy. Recent data support the specific therapeutic efficacy of valproate in certain subtypes of bipolar illness: rapid cycling variant, mixed mania, bipolar disorder associated with panic attacks, comorbid alcohol or substance abuse, with neurological features or secondary to organic illnesses. These features make valproate interesting as an alternative treatment for patients who generally respond less well to lithium or as a useful adjunct in the treatment of complicated patients who do not respond to single agents. However, further controlled studies are warranted to provide clear guidelines for the treatment with valproate.