Abstract: Research on valerian is in a strange situation. Aqueous extracts of the root reportedly have sedative effects on animals but only in irrelevantly huge doses. Some chemicals found in valerian roots do seem to calm or sedate man, but these substances (e. g. valepotriates) are apparently not present in aqueous or alcoholic extracts. So far the therapeutic employment of valerian root is a purely empirical one; its calming qualities are being considered by many pharmacologists as mere placebo effects.Experimental proofs that perfume compositions can have a calming action on rnan (Hanisch,1982) renews attention to the old hypothesis put forward by Daly and White in 1930 (British Journ. of Medic. Psychology 10, 70-87) that the alleviation of hysterical conditions by the administration of valerian may be due to its strong odour.Odour effects are covered by every day experience and can be deduced in terms of brain physiology from the close connection between olfactory centers and brain areas that are decisive for the appearance of emotions. The psychodynamical way of action could provide the key to the understanding of two facts: (1) valerian root is not suitable to force sleep contrary to the situation with the barbiturates or the major tranquillizers; (2) valerian does not induce sedation in all individuals, many of them are »nonresponders«.