Hepatocellular carcinoma is a malignant neoplasm of hepatocytes that is considered as the most common primary cancer of liver, the fifth most common malignancy worldwide, and the third leading cause of cancer death. It is a major health problem worldwide, due to its high incidence and high mortality rates. The principal goal of this book was to elucidate the antitumor efficacy of some natural products such as curcumin and carvacrol against N-nitrosodiethylamine-induced hepatocellular carcinoma in male rats with special concern on their mechanism of action. This book also sheds light on the role of sex hormone receptors gene expression in the pathogenesis of hepatocellular carcinoma. This work clearly demonstrated that curcumin and carvacrol have a promising therapeutic potential against hepatocellular carcinoma through their antiangiogenic, antiproliferative, and apoptotic effects.