In our search for potential stimulants of granulocyte-phagocytosis, more than 75 compounds isolated from higher plants have been investigated in the chemoluminescence-model for phagocytosis stimulating properties. The data were compared with those obtained from the microscopic test system. Both methods are suitable for systematic screening investigations. The alkaloids isopteropodin, emetin and aristolochic acid-Na, the sesquiterpenlactones helenalin and eufoliatin, the naphthoquinone plumbagin and the polysaccharides of Echinacea purp., Eupatorium perfol., Acanthopanax senticosus and Chamomilla recutita have been investigated in detail.