Abstract: The present paper surveys the occurrence of an active princeple, paeoniflorine, in genus Paeonia (Fam. Ranunculacea).From the phylogenetical point of view, the species with higher content of this compound occur mainly in the Sect. Paeonia (cf. Tab. 1.), among which Paeonia lactiflora and P. veitchii ranked as the two highest ones.In connection with the seasonal variations, the paeoniflorine contents of Paeonia lactiflora at different stages in Beijing were estimated. The results pointed out that there was a higher percentage of paeoniflorine content in the budding stage at the begining of May (cf. Tab. 2 and Fig. 1).In addition, a comparison of the paeoniflorine content of three kinds of Chinese traditional drugs, viz. "Chishao""Baishao" and "Mudanpi" was also made (cf. Tab. 4). Coupling the result with the use of these three drugs in Chinese traditional medicine, it was interesting to show that "Chishao" had the highest content of paeoniflorine and possessed, at the same time, mainly a "huoxue"(blood circulation mobilizing) action.