Much of the research on the strengthening of masonry structures has focused on strengthening of unreinforced masonry structures; as a result, most strengthening design guidelines are limited to this type of structural strengthening. In addition, only a limited experimental database of reinforced masonry structures with strengthening is available. The main purpose of this research is to study the behavior of fully grouted reinforced masonry walls strengthened with Fiber Reinforced Cementitious Matrix (FRCM) system under out-of-plane action. Seven reinforced masonry walls strengthened in flexure using (FRCM) were built as a part of this study. Two reinforced walls constructed in running and stack bond pattern were investigated as control specimens and the other specimens were strengthened using different types of fibers. FRCM strengthening composite materials consisted of one or two plies of fabric embedded in cementitious mortar. The test results indicated that the FRCM system is a very effective technique for upgrading flexural capacity of masonry walls and improve the behavior of stack wall.