Real Estate Investment Trusts are a class of coporations created by an set of Congress in U.S.A in I960, that quality for exemption from federal income taxation by conforming to certain requirements specified under the Internal Revenue Code. The most important requirements are that they must derive more than 75% of their gross income from real estate, and that, at least 95% of annual taxable income must be distributed to shareholder. So that it becomes taxable ar the shareholder level. Also, important are severe restrictions on the degree of ownership concentration, Thus REITs have a unique organizational form. In this article, we example the institutional structure of REITs and explain why the unique institutional environment of REITs might be expected to affect shareholder returns in mergers. Some other structure such as the UPREITs Corporate Structure and DOWNREITs Coporate Structure are also discussed. REITs become Lucrative for empirical studies of Capital Structure issues. It is from this perspective that REITs will remain to be an integral part of both Coperate and real estate finance. As a result, REITs will have come of age in the sense that they are now being more and more accepted as investment vehicles.