An experimental study on the strengthening of steel structures with FRP (Fiber Reinforced Plastic) is presented in this paper. Test coupons were prepared by applying FRP patches on both sides of steel coupons. Standard tensile tests were conducted to the test coupons. Two types of CFRP (Carbon Fiber Reinforced Plastic) and one type of GFRP (Glass Fiber Reinforced Plastic) were studied. The load and strain data were recorded, and the stiffness and strength were derived. The results show that CFRP provides better strengthening than GFRP, but there is no significant difference between PAN graphite/epoxy and pitch graphite/epoxy laminates.