Recently plants considered as a good source for new anti-cancer treatments due to their multiple chemical compounds. Many researchers recommended future studies to focus more on plant as a source for safe and effective anti-cancer treatment (s) and to detect their active ingredients and mechanism of action. Therefore, present book focused on clarifying the anti-cancer effects, mechanisms [i.e., apoptotic, anti-proliferative, anti-metastatic, anti-angiogenic effect (s)], and active ingredients of most of the medicinal plants found in the world against solid and/or hematological cancers.