BACKGROUND: The purpose of this review is to provide the Veterans Health Administration (VHA) with a broad overview of the effectiveness of aromatherapy and essential oils (EOs), and the health conditions for which these interventions have been examined. DATA SOURCES AND STUDY SELECTION: We searched multiple databases through February 2019 for systematic reviews (SRs) of aromatherapy and EOs for health conditions. Using pre-specified inclusion criteria, all abstracts and full-text articles were dual-screened for inclusion. When there were several qualified reviews for the same health condition, we selected a single review based on its recency, methods, scope, and applicability. DATA ABSTRACTION: From each review, we abstracted the focus of the SR, the number of controlled trials included, combined number of participants, duration of trials, condition treated, and relevant findings from controlled trials. We abstracted separate data for each of 5 outcome categories: psychological outcomes, nausea/vomiting, pain and other physical outcomes, sleep outcomes, and global health outcomes. DATA SYNTHESIS: For each review and outcome category we assigned values representing the effectiveness level of the intervention and confidence in the evidence and used these values to generate evidence maps. Additionally, we provide a narrative synthesis of the findings. RESULTS: We included 26 SRs representing the most recent and comprehensive evidence available. There is moderate-confidence evidence that aromatherapy is beneficial for pain in dysmenorrhea. Aromatherapy is potentially effective for pain in labor/childbirth; blood pressure reduction in hypertension; stress, depression, and sleep in hemodialysis patients; stress in healthy adults; anxiety in perioperative patients; and sleep quality in various populations, with low to moderate confidence in the evidence. For EOs applied topically, there is moderate confidence in the potentially positive effect of tea tree oil for tinea pedis. There is insufficient evidence of efficacy for all other conditions examined.