An experimental program was conducted to determine if a graphite fiber/resin matrix composite could be used to effectively reinforce a standard steel truck frame rail. A preliminary design demonstrated that the reinforcement weight could be reduced by a factor of 10 when compared to a steel reinforcement. A 1/3 scale rail section was fabricated to demonstrate low cost manufacturing techniques. The scale rail section was then tested and increased stiffness was confirmed. No evidence of composite fatigue was found after 500, 000 cycles. The specimen failed in bending at a load 50% greater than that predicted for a non-reinforced rail.