Our study was designed to determine the calcium and oxygen paradoxes in isolated rat hepatocytes, and to evaluate the cytoprotective effects of taurine on hepatocytes during oxygenation, hypoxia, and on these paradoxes. The calcium and oxygen paradoxes were clearly revealed in isolated rat hepatocytes. As the formation of the superoxide radical was accelerated by the hyperbaric conditions and the calcium ions, drugs such as superoxide dismutase and a calcium channel blocking agent (verapamil), prevented these paradoxes. Taurine decreased the oxygenation-induced lipid peroxidation of hepatocytes, and prevented the hypoxia-induced hepatocyte death in a calcium-containing medium, but not in a calcium-free medium. Taurine also protected the hepatocytes from injuries associated with the calcium and oxygen paradoxes due to the inhibition of sudden calcium influx into the hepatocytes.