The research deals with conducting a questionnaire to evaluate the perceptions of the parties to the administrative contracts in the construction public sector, including owners, consultants, and contractors, regarding the causes and effect of delay in project implementation in Egypt in order to determine the main reasons and the impact on them, and then find out the various ways to improve the economy in this important sector. A comprehensive list consisting of (21) ones has been identified. Thirty effects were conducted through a review of the literature, studies and research that dealt with that field, and through interviews with specialists, a comparative study was conducted with other previous works on the most important effect of delay in construction projects. Which resulted in identifying the most important of these causes and their impact using the Relative Importance Index (RII), which is the most widely used method in analyzing the causes and the extent of their impact in the short and long term. The study and analysis concluded with (10) ten main causes of delay in construction industry projects and their impact on creating many Restrictions that represent an obstacle to achieving the desired goals, which in turn negatively affect the economy of the Arab Republic of Egypt.