Essential oils are ingredients of cosmetic and health care products as well as massage oil used in aromatherapy. There is no doubt that essential oils and their components are able to permeate human skin. But information is rare dealing with percutanous absorption of essential oils in more detail. In this paper we investigated the in vitro skin permeation of monoterpenes and phenylpropanoids applied in pure rose oil and in form of neat single substances. We found that the application form had an exceeding influence on the skin permeation behaviour of the compounds. For substances applied in rose oil a clear relationship between their lipophilic character, chemical structure, and skin permeation could be confirmed. Regarding the P(app)-values the substances are ranked in the order: monoterpene hydrocarbons < monoterpene alcohols < monoterpene ketons < phenylpropanoids. In contrast, for neat single substances there were no relationships between their lipophilic characters, structures and skin permeation. Furthermore, except for alpha-pinene and isomenthone, the P(app)-values of all other substances were several times higher when applied in pure native rose oil than in their neat form. This suggests that co-operative interactions between essential oil components may promote skin permeation behaviour of essential oil and its components.