The use of complementary and alternative medicine (CAM) is common among patients with cancer. Many of these patients use CAM therapies to decrease the risk of late effects that are sometimes associated with cancer therapy. Certain classes of effective anticancer agents can induce short- and long-term toxicity to the liver. Currently, there are no safer alternatives to these medications. Milk thistle (Silybum marianum) is a botanical that may be useful in the prevention or treatment of liver dysfunction in patients undergoing anticancer therapy.