Objectives: The objective of this review is to systematically review the evidence for the effectiveness of aromatherapy in the treatment of high blood pressure. Methods: Twelve databases were searched from their inception through December 2009. Controlled trials testing aromatherapy in patients with hypertension of any origin that assessed blood pressure were considered. The selection of studies, data extraction and validations were performed independently by two reviewers. Results: One randomized clinical trial (RCT) and four non-randomized controlled clinical trials (CCTs) met our inclusion criteria. The one RCT included tested the effects of aromatherapy as compared with placebo and showed significant reduction of systolic blood pressure and diastolic blood pressure. All of the four CCTs showed favourable effects of aromatherapy. However, all of the CCTs also had a high risk of bias. Conclusion: The existing trial evidence does not show convincingly that aromatherapy is effective for hypertension. Future studies should be of high quality with a particular emphasis on designing an adequate control intervention.