Nowadays, cancer is the leading cause of death in many countries of the world. Chemotherapy is a common treatment strategy for advanced and metastatic cancer. However, the cost of chemotherapy is a major concern in developing countries. In addition, resistance and negative side effects resulting from chemotherapy with conventional anti-cancer drugs pose some limitations in clinical use. Consequently, herbal medicine remains an inevitable alternate or adjunct therapy for cancer pre-vention and treatment. Various plant components with bioactive compounds and derived natural products are being intensively investigated to explore their potential for prevention and treatment of cancer. Houttuynia cordata Thunb. (known in Thai as Plu-Kao) is a medicinal herb indigenous to many parts of East and Southeast Asia including Thailand. The plant has been recognized as possessing many biological and pharmacological properties including anticancer, antioxi-dative, antiviral and immunomodulatory activities. The fermented H. cordata has been demonstrated to ex-hibit cytotoxic effects on human leukemia cells and he-patocellular cancer cells to a considerable extent.