Cardiac effects of drugs used for circulatory disorders in traditional Japanese medicine based on ancient Chinese medicine (Kampo Medicine): Saikoka-ryukotsu-borei-to, Oren-gedoku-to, Toki-shakuyaku-san, Shimbu-to, Moku-boi-to, Ryo-kei-jutsu-kan-to, Sha-kanzo-to, Keishi-ninjin-to, Toki-to and Ryo-kan-kyo-mi-shin-ge-nin-to were investigated using canine isolated, blood-perfused sinoatrial node and papillary muscle preparations. Single injections of small doses of Oren-gedoku-to, Moku-boi-to and Ryo-kan-kyo-mi-shin-ge-nin-to (0.1 to 3 mg) dose-dependently increased the sinoatrial rate and the developed tension of papillary muscle, while other drugs showed almost no effect on these parameters. All the drugs had almost no effect on the blood flow through the nutrient arteries of each preparation. The positive chronotropic and inotropic effects induced by Oren-gedoku-to, Moku-boi-to and Ryo-kan-kyo-mi-shin-ge-nin-to did not show tachyphylaxis and were not affected after pharmacological denervation by tetrodotoxin treatment or by reserpine pretreatment, but were significantly suppressed by atenolol. These results indicate that these three drugs act as beta-adrenoceptor agonists to produce clinically useful cardiac effects.