Résumé : Although awareness on bipolar disorder has increased during the last decade, this condition remains characterized by a disabling burden, in terms of morbidity and functional impairment. This paper aims to review some critical issues in the current knowledge on-Bipolar disorder. Although large European epidemiological studies are lacking, Bipolar disorder is characterized by a set of severe features, including an early age of onset, a chronic outcome and an important suicidal risk. A majority of bipolar patients also experience a comorbid Axis I condition, including substance abuse, anxiety disorder and attention-deficit hyperactivity disorder. This situation presents a therapeutic challenge, since antidepressants or methylphenidate may be associated with the risk of inducing mania. Recently, a large number of studies have provided evidence for the efficacy of new compounds in the treatment of both mania and bipolar depression, but also in long-term relapse prevention. Recent research has also allowedfor the redefinition of the concept of mood stabilizer and for improving existing guidelinesonthe clinical management of Bipolar disorder. ©2007 Elsevier B. V and ECNP.