© 2016 Elsevier Ltd Bipolar disorder (BD) is the episodic disturbance of mood into depression or elation. Bipolar I disorder is defined by mania, bipolar II disorder (BD-II) by major depression and hypomania. BD is heritable: many gene variants contribute. Anxiety co-morbidity is common. Management usually requires long-term medical treatment. Because BD combines chronicity with considerable patient autonomy, psycho-education is also a key. Severe manic episodes should be treated with an oral dopamine receptor antagonist/partial agonist or valproate. The treatment of bipolar depression is controversial. For an early treatment effect, quetiapine, lurasidone (unlicensed indication) or olanzapine can be useful. Lamotrigine is underused: it requires dose titration but is well tolerated and a possible monotherapy in BD-II. An antidepressant is not recommended as monotherapy for bipolar patients. Relative or even marked treatment resistance can occur in depressed bipolar patients. Medicines available for long-term treatment are often more effective against one illness pole than the other, so are often used in combinations dictated by the burden of illness. If this is predominantly mania, the most anti-manic agents (e.g. lithium, valproate, a dopamine receptor antagonist/partial agonist) are combined; if depressive, lamotrigine, quetiapine, lurasidone or olanzapine can be more appropriate. Long-term antidepressant use can be justified if patients relapse on discontinuation.