Objective: The objectives of this report are to a) review the clinical manifestations and therapy for REM Sleep Behavior Disorder in older adults with depression and b) explore the potential benefits of mirtazapine use for this condition. Methods:A case report of an 85-year-old male with symptoms of REM Sleep Behavior Disorder and Depression.Results: Symptoms of depression and disordered sleep improved after initiation of low dose mirtazapine. Conclusion:Mirtazapine could be considered as a potential therapy for REM Sleep Behavior Disorder in patients with concurrent depression.