Reinforced concrete structures are subjected to many causes of distress throughout the service life. Generally, beams are the more critical structural elements that may suffer from partial or total collapse as a result of distress action. Repair of distressed reinforced concrete beams have been under investigation for a number of years ago to achieve the best, cheapest, casiest, more executable and more economical methods of repair. The distress causes, the programming of repair, the widely used techniques of repair, strengthening of defected structures and the common repair and strengthening methods of reinforced concrete beams with special attention to flexural behavior are presented in this thesis. Four main methods of repair were tested in present study to examine the behavior and efficiency of the repaired beams in flexure under two equal concentrated loads. In the first method, a steel plate was glued and bolted to the bottom face of the beam. In the second one, a steel channel was used instead of steel plate. In the third method, the steel channel was glued to the bottom face of the beam as before but also bolted to the beam flange. In the fourth one, the steel plates are glued only but with using epoxy adhesive mortar dowels instead of the steel bolts. Unlike most of the previous investigations, the tested beams were loaded to certain percentages of the beams ultimate design capacity before carrying out the repair process. Sixteen simply supported reinforced concrete half scale T-beams were loaded, repaired and then reloaded and tested again by means of 4-points loading system (two supporting & two concentrated loading points). Many variables were considered such as the preloading level prior to the repair process, steel plate length and the bolt length. Very important results were obtained. Some relations and recommendations which may be useful for designers before choosing the technique and carrying out the repair process were introduced.