Epirubicin (trade name: Falmorubicin) is a stereoisomer, in which the hydroxyl group of doxorubicin is inverted at position 4', and has the similar mechanism of action as that of doxorubicin; namely, this new anthracycline anticancer agent for injection shows a wide antitumor spectrum and strong antitumor activity via the inhibition of DNA and RNA synthesis. In non-clinical experiments, the effect of epirubicin on transplantable murine tumors was similar or superior to that of doxorubicin in rats and mice. As for pharmacodynamics, this drug was found to rapidly penetrate into the tissue from the blood, and to remain there for a long period of time. This drug has been widely used abroad for the treatment of various solid cancers, such as breast cancer, and tumors of hematopoietic organs, such as malignant lymphoma. In Japan, it was proved clinically that the drug was effective on a wide range of tumors, including acute leukemia, malignant lymphoma, breast cancer, ovarian cancer, gastric cancer, hepatic cancer and ureteral epithelioma(bladder cancer, renal cancer and ureteral cancer). In a comparative study of chronic cardiotoxicity, it was noted that epirubicin produced less damage to the myocardium than doxorubicin when every morphological change was examined as an indicator. Electrocardiographic and histopathological findings also disclosed that epirubicin exhibited a smaller effect on the myocardium than that of doxorubicin. In conclusion, epirubicin is a new antitumor agent having an antitumor effect similar or superior to that of doxorubicin with the various toxicities, including cardiotoxicity, which are reduced in this drug in comparison to those of doxorubicin.