It is shown that the flavonoid pulikarin suppresses activity of an adenylate cyclase and reduces level intracellular [Ca 2+ ], perhaps its effect is connected with inhibition of a gain of cytoplasmatic Ca 2+ as at the expense of its entrance outside, and release from intracellular storages. Perhaps, oppression of fluorescence of membrane-bound Ca 2+ is connected with inhibition of a pulikarin of release of calcium from intracellular depots. The inhibiting effect of a pulikarin on ADP-induced aggregation of platelets is connected with oppression of a gain of cytoplasmatic concentration of Ca 2+ from depot of platelets.