 Research Background: While the efficacy of lithium in the treatment of acute mania has been established by numerous studies, it is also known that up to 50 of the patients fail to respond when it is prescribed alone. It is therefore common practice to complement the treatment, most commonly with antipsychotics and benzodiazepines. It has been suggested that antipsychotic agents are faster acting and are superior in controlling hyperactivity compared to lithium, whereas mood stabilisation is better achieved by lithium, Typical antipsychotics, such as chlorpromazine, may therefore be useful as adjunctive medication to mood stabilisers, especially within the first few weeks of treatment of acute mania, and for patients exhibiting psychotic symptoms or hyperactivity. They however can induce side effects somnolence, dizziness, dry mouth, extrapyramidal side effects such as rigidity of the muscles, and possibly tardive dyskinesia involuntary movements or contraction of muscles, as well as akathysia sense of restlessness. They finally have been suspected to contribute to the occurrence of post-manic depression. Recent publications in chronic populations have shown that atypical antipsychotics, such as olanzapine, are also an effective adjunctive treatment. Olanzapine has the important advantage to induce a very low incidence of extrapyramidal side effects, including tardive dyskinesia. It can however induce somnolence, dizziness, dry mouth, and rather commonly weight gain. Moreover, some authors have reported that olanzapine might induce mania. Both treatments appear then to have positive effects as well as undesirable side effects. Our project is to compare them. The literature concerning first episode mania is sparse, particularly in the domain of pharmacotherapy. One retrospective study showed that 77 of the patients received antipsychotics at discharge and 25 at 6 months follow-up. No comparison has however been made between typical and atypical antipsychotics, and there are no specific treatment guidelines of first episode mania with psychotic features. 