Echinacea-containing drugs have to be classified according to the used plant species (Echinacea purpurea, E. pallida or E. angustifolia), the processed part of the plant (root, upper parts or whole plant), and the mode of processing. Significant pharmacological effects have been found in vitro and in vivo for the expressed juice of the upper parts of E. purpurea and for alcoholic extracts of the roots of E. pallida, E. angustifolia and E. purpurea. The activity is mainly directed towards the nonspecific cellular immune system. Several active constituents are discussed: polysaccharides, glycoproteins, caffeic acid derivatives (cichoric acid) and alkamides.