Purpose: The purpose of this study is to identify the effects of aromatherapy on agitation in patients with dementia using a meta-analysis and systemic literature review. Methods: The EMBASE, CINAHL, MEDLINE, and other databases were searched up to November 2017. Results: Of 419 publications identified, 12 met inclusion criteria, and 9 studies were used to estimate the effect size of aromatherapy. A total of 837 participants across all studies were included. The commonly applied methods were massage (50%), type of oil lavender (75%), and instrument Cohen-Mansfield Agitation Inventory (75%). A medium effect size of aromatherapy on agitation was identified (d=-0.56, I²=65.0%, p=.001). The massage group has lower effect size than the other group (d=-0.98, I²=0.0%, p=.001). Conclusion: Aromatherapy appears to be effective in improving agitation in patients with dementia. However, further studies for home-dwelling patients with dementia and with different types of aroma oil should be conducted in the future. In addition, research with well-designed are needed to assess the effects or aromatherapy on agitation.