OBJECTIVE： To compare clinical efficacy and safety of olanzapine and quetiapine for mental disorders elderly patients. METHODS： 120 elderly patients with mental disorders were randomly divided into olanzapine group and quetiapine group， with 60 cases in each group. Olanzapine group was given Olanzapine tablet orally with initial dose of 2.5 mg， qd， and then increasing to maximal dose 15 mg according to disease condition， qd； quetiapine group was given Quetiapine tablet orally with initial dose of 50 mg， qd， increasing to maximal dose 400 mg according to disease condtion， qd. Both groups received 6 weeks of treatment. Clinical efficacy of 2 groups were compared as well as PANSS and the quality score of life before and after treatment， and the occurrence of ADR.  RESULTS： PANSS and the quality score of life were improved significantly in both groups， with statistical significance （P＞0.05）； but there was no statistical significance between 2 groups （P＞0.05）. There was no statistical significance in clinical efficacy between 2 groups （P＞0.05）. The incidence of lethargy， hypotension and bradycardia in quetiapine group were significantly lower than in olanzapine group， while the incidence of tachycardia was significantly higher than olanzapine group， with statistical significance （P＜0.05）. CONCLUSIONS： Olanzapine and quetiapine are similar to each other in the treatment of mental disorders elderly patients； both of them can effectively improve the quality of life， and ADR induced by quetiapine is slighter than that induced by olanzapine.