The use of advanced composite materials (FRP) is rapidly growing and has exciting applications in bridge construction. These materials are light, have an excellent resistance to corrosion, and high strength. Because of these advantageous properties, structures reinforced with composite materials are lighter and have longer service life than those reinforced with steel.  On the other hand, the composite materials are very expensive as compared to steel. However, the severity of this problem can be minimized by using optimization techniques that achieve optimum design with minimum cost.  In this research, an optimization technique is used to minimize the superstructure cost of two types of bridge systems (slab-on-CPCI girder bridges and Nebraska all-precast bridge systems) reinforced or prestressed (pretensioned) with Carbon Fiber Reinforced Polymers (CFRP).  The objective of this research is to show that optimization techniques are the most efficient tools in dealing with this kind of tedious design procedure (design of prestressed concrete bridges) that is normally an iterative process based on trial and error. Furthermore, the technique adopted in this investigation can be used for minimizing the cost of structures reinforced with FRP. As a result, these tools can be used in developing design aids that can be used to achieve optimum bridge designs.