This review focuses on studying the pharmacological effect of cyclic peptides as anti-cancer drugs. There are many examples which are already used to treat cancer, either directly or in the treatment of episodes associated with cancer tumors. Goserelin acetate; is an anti-cancer drug, trade name Zoladex, is an injectable gonadotropin releasing hormone superagonist. Leuprolide acetate; is a gonadotropin-releasing hormone or luteinizing-hormone-releasing hormone analog used in the treatment of hormone-responsive cancers such as prostate cancer or breast cancer. Somatostatin, (SST), is a peptide hormone; the peptide hormone somatostatin regulates the endocrine system, affects neurotransmission and cell proliferation via interaction with G protein-coupled somatostatin receptors and inhibits the release of numerous secondary hormones. Octreotide: is a somatostatin mimic, trade name sandostatin, Octreotide is also a more potent inhibitor of growth hormone, glucagon, and insulin than the natural hormone. On the other hand there are many natural bioactive peptides: derived from different foods represent another source of health-enhancing or cancer fighting compounds. Different studies indicate that it is possible that many of these peptides may be released during digestion in the human stomach or during food processing from various plant and animal proteins, especially milk, soy, and fish proteins, for examples Depsipeptides and Argyrins.