The aim of this study was to investigate the effects of ylang ylang oil (Cananga odorata, Annonaceae) on human physiological parameters and self-evaluation after transdermal absorption. Forty healthy volunteers participated in the experiments. Physiological parameters recorded were skin temperature, pulse rate, breathing rate and blood pressure. Self-evaluation was assessed by means of visual analog scales (VAS). The ylang ylang oil caused a significant decrease of blood pressure and a significant increase of skin temperature. At the behavioral level, subjects in the ylang ylang oil group rated themselves more calm and more relaxed than subjects in the control group. These findings are likely to represent a relaxing effect of the ylang ylang oil and provide some evidence for the usage of the ylang ylang oil in aromatherapy such as causing a relief of depression and stress in humans. Copyright © 2006 John Wiley & Sons, Ltd.