The drug Bellidis flos is used in therapy as a diuretic and an expectorant agent. Its principal constituents are saponins. The paper examined the haemolytic activity of the drug obtained by the collection of the capitula of Bellis perennis L. in a onemonth interval (from March to October) in the course of three years. The determination of haemolytic activity was carried out following the method of Pharmacopoea Bohemoslovaca IV. It has been found that the haemolytic activity of the drug changes in dependence on the time of collection of capitula during the year; it is lowest in March, then it increases, reaching the maximum in summer months (June, July, August), and then it decreases again.

        Key words: Bellis perennis L. – Bellidis flos – saponins – haemolytic activity – seasonal changes