Angiogenesis can be explained as the growth of new blood vessels from pre-existing vasculature. It has an important and vital role in growth and development, as well as in wound healing. Anti-angiogenic substances suppress the growth of new blood vessels so prevent nutrients and oxygen needed for the growing of tumor cells. It is proposed that tumor angiogenesis could serve as a potential target for anticancer therapy. Combretastatin (CA-4) is an anti-angiogenesis agent that inhibits the tubulin polymerization. CA-4 exhibits anti-tumor effects through the well-organized therapeutic mechanism of tumor blood supply disabling. By affecting selectively and blocking tumor vasculature, CA-4 reduces the blood supply needed for tumor growth and survival. As a result of oxygen poverty and build-up of tumor metabolic by-products causes the death of the cancer cells within the central core of the tumor. In this thesis, covalent modification of CA-4 has been investigated. Variety of CA-4 analogs which involved blocking the free alcohol group has been synthesized.