Resibufogenin (RBG) is a single compound isolated from Chansu, a traditional Chinese medicine obtained from the skin venom gland of the toad. Formulations of Chansu have been widely applied in China, Japan, and other Asian countries for a long time and are currently used as alternative medicines. However, there have been several reports about the toxicity of Chansu and its medical formulations in the United States recently. As digitalis, RBG possesses both pharmacologic and toxicologic effects. According to our study results, RBG, one of major ingredient of Chansu, induced delayed afterdepolarization and triggered arrhythmias both in cardiac fiber in vitro and in beating heart in vivo at the high concentrations. The electrophysiologic toxic effects of RBG, the possible mechanism of toxicity, and treatment possibilities are discussed in the present review