Developing countries have many cities which contain a historic district that include older buildings and streets as well as traditional activities and/or events. Such historic districts have survived and not changed to match the new developments. However, the continuing pressure of the population growth and the geographic expansion often represents a serious threat to these heritage assets which thought of as a block in the way of advance. This paper discusses the implementation of the heritage economics principles and its methodologies in the investment appraisal for the preservation of heritage assets in developing cities and countries, taking into consideration the characteristics of cultural heritage in such environment and discusses the options and anticipations that might face the planners of urban areas. The paper also summarizes the methodology used for the investment appraisal in the projects that aim at reusing the assets of material heritage. It also explains and gives information about the traditional status of developing countries; that's to clarify the implementation of post-investment assessment techniques on the projects concerned with the preservation of heritage assets in developing countries.