Bipolar disorder, with mood swings between depression and mania, may affect up to 1.5% of adults, and increases the risk of suicide and disability. Most people improve over time, but two thirds may have residual dysfunction, and at least 40% may have recurrent episodes.We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments in people with mania associated with bipolar disorder? What are the effects of treatments in bipolar depression? What are the effects of interventions to prevent relapse of mania or bipolar depression? We searched: Medline, Embase, The Cochrane Library and other important databases up to July 2006 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).We found 60 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.In this systematic review we present information relating to the effectiveness and safety of the following interventions: antidepressants, carbamazepine, chlorpromazine, clonazepam, cognitive therapy, education, family-focused psychoeducation, gabapentin, haloperidol, lamotrigine, lithium, olanzapine, psychological treatments, quetiapine, risperidone, topiramate, valproate, and ziprasidone.