To find out whether the Chinese drug Radix Aconiti Carmichaeli is compatible with another Chinese drug Rhizoma Pinelliae in preparation, the two medicinal herbs were made into different forms of decoctions. Experiments with these decoctions were carried out to observe the action on isolated hearts of toads and the ECG and acute toxicity on mice. The results showed that in terms of toxicity there was no marked increase in the mixed decoction as compared with the other two decoctions prepared from Radix Aconiti Carmichaeli and Rhizoma Pinelliae separately.