In order to clarify the pharmacological properties of some constituents of the essential oil of Valeriana officinalis L. s. 1. four pure compounds (valerenal, valerenic acid, valeranone and isoeugenyl-isovalerate), a hydrocarbon fraction, an oxygen fraction and the essential oil itself were submitted to a screening test. This test is an elaboration of the screening test of CAMPBELL and RICHTER [11] to which several symptoms mentioned by IRWIN [12] and some other features have been added. From the results of this so-called Syndrome test valerenal and valerenic acid, which show some structural correspondence with the valepotriates, are pharmacologically active at the lowest dose levels. Together with valeranone, both compounds are likely to play a significant role in the depressive action of the essential oil whereas the activity of isoeu-genyl-isovalerate is of relatively minor importance.