Background: Acne is a prevalent, chronic, and sometimes severe skin disorder affecting an estimated 85% of adolescents and 50% of adults older than age 20 years. The psychosocial implications of acne can be considerable, often continuing long after physical symptoms resolve. Although effective acne medications are available, most exhibit adverse-effect profiles that can leave the patient with few effective treatment options. Emerging evidence indicates that plant-derived essential oils may be a biologically plausible treatment for acne, although high-quality evidence of effectiveness and safety is lacking. Objective: To examine the clinical effectiveness and cost-effectiveness of essential oils and aromatherapy for the treatment of acne. Design: This randomized, wait-list controlled trial will have three parallel groups; 192 participants with acne vulgaris, aged 16-45 years, will be recruited primarily through eight Technical and Further Education campuses across Adelaide, South Australia. Participants will be randomly assigned to standard essential oil blend, customized aromatherapy treatment, or wait-list control. Changes in the physical and psychosocial symptoms of acne will be assessed at baseline and 6 and 12 weeks by using the Leeds Acne Grading System, Assessment of Quality of Life-8 Dimension instrument, and Acne-Specific Quality of Life instrument. Costs of treatment will be measured on the basis of resource inputs and unit costs and will be limited to acne treatment. The clinical effectiveness and cost-effectiveness will be compared between each intervention and against usual care, using standard health economic techniques. Conclusions: The provision of high-quality evidence of the effectiveness of essential oils and aromatherapy in the treatment of acne may help consumers make better-informed choices about acne management. Insights gained from this research will also contribute to the academic field of complementary medicine, specifically aromatherapy, for which the evidence base is extremely limited.